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THE  MAGIC  LANTERN  MANUAL. 


•i, 


\ 


The  Microscope  Lantern . — p.  134.  Frontispiece. 


THE 


MAGIC  LANTERN 
MANUAL. 

(SECOND  EDITION.) 

BY 

W.  I.  CHADWICK. 

{Hon.  Sec.  Manchester  Photographic  Society . 

WITH 

ONE  HUNDRED  AND  FIVE  PRACTICAL  ILLUSTRATIONS. 


NEW  YORK : 

SCOVILL  MANUFACTURING  COMPANY, 

423  Broome  Street, 

W.  IRVING  ADAMS,  Agent. 

1886. 


Digitized  by  the  Internet  Archive 
in  2016 


https://archive.org/details/magiclanternmanuOOchad 


PREFACE  TO  THE  SECOND  EDITION. 


HE  writer  hopes  to  be  acquitted  of  presuming  to  teach  many 


new  things  to  his  brother  lanternists  by  this  little  treatise; 
he  is  actuated  rather  by  other  motives  in  giving  a few  practical 
explanations  and  descriptions  of  the  various  forms  of  Magic 
Lanterns,  with  their  details  and  application ; and  although  form- 
ing a book  of  instruction  to  the  learner,  he  trusts  it  will  take  its 
place  as  a handbook  to  the  expert  lanternist. 

In  the  inquiry  for  a New  Edition  of  this  little  work,  opportunity 
has  been  taken  to  subject  the  whole  matter  to  close  scrutiny  and 
revision,  and,  consequent  upon  the  development  of  this  particular 
subject,  it  has  been  found  necessary  to  make  such  additions  as  is 
thought  sufficient  to  cover  any  new  ground  up  to  date. 


W.  I.  CHADWICK. 


Eccles,  near  Manchester , 

March  27th)  1885. 


CONTENTS. 


Introduction 

Page 

9 

The  Magic  Lantern 

12 

Optical  Arrangements 

...  12 

Objectives 

17 

The  Sciopticon 

21 

The  Magnesium  Lantern 

27 

The  Lime  Light 

29 

Electric  Light 

29 

The  Ethoxo  Lime  Light 

52 

Photometry 

62 

Dissolving  Views  ... 

...  64 

The  Biunial  Lantern  ... 

. 71 

The  “Luke”  Biunial  Lantern 

73 

Dancer’s  Lantern 

75 

Chadwick  s*Lantern 

76 

The  Triple  Lantern 

77 

Beechy's  Lantern  ... 

79 

Keevil’s  Lantern 

81 

The  Opaque  Lantern 

...  S3 

Stand  for  the  Lantern 

84 

Screens 

86 

Lantern  Slides 

88 

Production  of  Photographic  Slides  .. 

91 

Carbon  Transparencies 

99 

Mounting  of  Lantern  Slides 

104 

Carriers 

106 

Statuary 

112 

The  Colouring  of  Slides 

114 

Effect  Slides 

n8 

Mechanical  Slides 

121 

Viewing  Pictures  ... 

125 

Descriptive  Lectures  ... 

127 

Reading  Desk 

128 

Scientific  Projections  ... 

130 

THE  MAGIC  LANTERN  MANUAL, 


INTRODUCTION. 

SO  much  has  previously  been  said  and  written  on  the  value 
and  merits  of  the  Magic  Lantern  as  an  instrument  for 
instruction  and  amusement,  that  the  author  does  not  think  it 
possible  to  add  much  interest  by  enlarging  upon  what  is  already 
known.  But  for  the  benefit  of  those  readers  who  may  not  have 
studied  the  Magic  Lantern,  it  may  be  remarked  that  within  the 
last  ten  years  this  instrument  has  become  much  more  popular  than 
for  some  time  previous.  By  the  introduction  of  the  “ Sciopticon  ” 
there  is  little  doubt  that  a new  interest  was  awakened — that  instru- 
ment admirably  filling  up  the  wide  gap  between  the  old-fashioned  oil- 
lit  lantern  and  the  more  elaborate  oxy-hydrogen  instrument,  about 
all  of  which  something  will  be  said  by-and-bye.  More  recently  a 
keener  interest  still  has  been  developed,  as,  by  the  introduction  of 
the  gelatine  process  of  photography,  the  number  of  amateur 
photographers  in  this  country  has  been  more  than  doubled.  The 
photographer  soon  discovers  that  there  is  no  more  enjoyable  way 
of  exhibiting  his  productions,  and  reciting  the  pleasures  of  his 
rambles,  than  by  means  of  his  lantern. 

Many  different  ways  of  applying  the  Magic  Lantern  present 
themselves,  perhaps  none  more  pleasing  than  its  adaptation  to 
Dissolving  Views,  which  were  invented  by  Mr.  Child,  the  method 

9 


xo 


THE  MAGIC  LANTERN  MANUAL. 


of  their  production  being  long  kept  a secret  by  him.  These 
charming  effects  were  then  produced  as  now,  viz.,  by  two  lanterns 
provided  with  suitable  arrangements  for  gradually  cutting  off  the 
picture  of  one  lantern,  and  disclosing  that  of  the  other  by  alter- 
nately shutting  out  the  light  from  each  lantern.  Ever  since  their 
introduction  they  have  formed  an  everlasting  source  of  amusement 
and  instruction  at  many  scientific  institutions  throughout  the 
country.  To  give  some  idea  of  the  public  appreciation  of  such 
exhibitions  when  properly  conducted,  it  may  be  stated  that  at  an 
exhibition  of  photographs  of  statuary  given  in  this  way  at  the 
Manchester  Mechanics’  Institution  some  years  ago,  over  seven 
hundred  pounds  were  realized  in  a few  weeks. 

The  popularity  of  the  instrument  has  increased  by  its  use  to  the 
photographer  for  enlarging  purposes,  and  in  many  other  ways  its 
utility,  combined  with  photography,  has  of  late  placed  it  as  an 
indispensable  apparatus  to  the  science  teacher,  &c. 

The  simplification  of  oxygen  gas-making  for  the  lime  light 
lantern  has  also  played  its  part  by  placing  powerful  lights  in  the 
hands  of  almost  inexperienced  persons,  with  whom  the  manu- 
facture of  oxygen  gas,  in  the  old  form,  was  a dreaded  affair,  and 
one  only  to  be  read  about.  However,  these  fears  are  now  of  the 
past,  and  exhibitions  by  the  oxy- hydrogen  lime  light  may  now 
be  conducted  on  from  20  to  30  feet  screens  with  almost  as  little 
trouble  and  risk  of  accident  as  with  the  ordinary  oil  light.  This 
has  only  to  become  more  widely  known  to  again  multiply  our 
lanternists,  and  let  us  hope  that  before  long  every  schoolmaster 
and  educational  teacher  may  be  possessed  of  one  or  other  form  of 
this  useful  instrument. 

Perhaps  nothing  could  have  enlivened  the  spirit  of  lantern 
exhibitions  so  much  as  photography,  for  now  we  are  able  to 
procure  at  a cheap  rate  photographic  slides  of  almost  every 


INTRODUCTION . 


II 


country  in  the  world,  and  these,  as  well  as  being  arranged  in 
series,  can  be  obtained  with  excellent  descriptive  lectures  accom- 
panying the  different  sets. 

Of  late  years  photographic  dry  plates,  the  extreme  of  simplicity 
in  preparation,  have  been  brought  to  a high  state  of  perfection, 
and  the  whole  manipulation  reduced  to  simple  rules,  so  that  every 
tourist  may  become  a photographer. 

Cameras  and  apparatus  have  also  had  the  careful  consideration 
of  both  home  and  foreign  makers,  the  result  being  that  cameras 
for  pictures  up  to  stereoscopic  and  cabinet  size,  not  exceeding  one 
pound  in  weight,  may  be  carried  in  the  pocket,  with  a stand  for 
holding  same  in  the  portable  form  of  a walking-stick,  umbrella,  or 
alpenstock.  So.  that  a tourist  may  set  off  on  his  travels  with  his 
photographic  apparatus  in  his  pocket,  and  may  return  with  thirty 
or  forty  souvenirs  of  places  visited  without  the  inconvenience  of 
extra  luggage.  Thus  holiday  rambles  may  be  by  the  aid  of  photo- 
graphy illustrated  and  described,  and  continental  tours  be  made 
the  subject  of  enjoyable  and  everlasting  reminiscences,  reproduced 
by  aid  of  the  lantern  to  our  friends  at  home  with  almost  living 
majesty. 

Lectures  and  slides  upon  astronomy,  natural  philosophy,  and  in 
fact  most  other  branches  of  science  and  art,  are  to  be  purchased 
already  arranged.  Temperance  tales,  fairy  tales,  comic  stories, 
and  lessons  for  the  young  are  obtainable  (either  by  purchase  or 
hire),  and  still  our  producers’  lists  are  not  complete,  and  a bound- 
less ocean  is  open  to  those  who  are  willing  to  embark  in  the 
buoyant  ship  Industry,  navigated  by  Captain  Perseverance  and 
his  honoured  crew,  with  Fortune  at  the  helm. 


2 


12 


THE  MAGIC  LANTERN  MANUAL. 


THE  MAGIC  LANTERN. 

THE  Magic  Lantern  of  to-day  is  in  principle  the  same  as  con- 
structed by  Kircher  about  the  sixteenth  century,  and  de- 
scribed by  him  in  his  book  “ Ars  magna  lucis  et  umbra”  although  it 
would  appear  that  Cellini  must  have  used  some  such  instrument  a 
century  previous  to  produce  phantom  figures  in  the  smoke  of  a fire. 
The  principal  arrangements  of  the  instrument  consist  of  an  illu- 
minating power  (Fig.  i),  with  a 
lens  called  a condenser  (c)  placed 
between  the  light  and  the  picture 
(s).  In  front  of  this  latter  is 
placed  another  lens,  styled  an 
objective  (o).  A light-tight  box 
encloses  the  whole,  and  prevents 
the  emission  of  light,  except 
through  the  lenses  above  men- 
tioned. 

It  will  be  perhaps  as  well, before 
entering  into  the  illuminating 
powers  and  various  forms  of  lan- 
terns, to  describe  the  optical  por- 
tions of  the  arrangement. 


OPTICAL  ARRANGEMENTS. 

The  Condenser  is  for  the  purpose  ot  collecting  as  many  of  the 
rays  of  light  as  possible,  and  transmitting  them  through  the  picture 


CONDENSERS. 


13 

on  to  the  screen.  This  being  understood,  we  will  now  consider 
the  best  form  and  size  for  our  requirements.  There  are  differences 
of  opinion  as  to  the  best  form  of  condenser  for  the  Magic  Lantern. 
At  this  there  is  no  need  for  surprise,  as  the  writer  has  frequently 
heard  lanternists  expressing  opinions  in  matters  concerning  the 
optical  arrangements,  although  possessed  of  but  a very  imperfect 
optical  knowledge,  and  in  some  cases  ignorant  of  the  object  of  the 
various  arrangements.  One  of  the  most  primitive  forms  of  con- 
densers is  the  simple  plano-convex  lens,  or  common  bull’s-eye. 
This  collects  a certain  quantity  of  light  on  the  one  side  and  dis- 
tributes it  on  the  other  (the  convex  side) ; but  as  these  “ bull’s- 
eyes  ” are  never  of  short  focus,  they  require  to  be  farther  from  the 
light,  and  thus  the  angle  of  illuminating  power  collected  is  small. 
For  it  will  be  shown  that  in  two  condensers  of  unequal  foci— main- 
taining the  same  diameter — the  angle  of  light  collected  by  each 
separately  would  differ  in  proportion  to  the  square  of  the  distance 
between  the  light  and  the  condensers  : thus,  a 4-inch  condenser, 
5 inches  distant  from  the  light,  would  only  receive  one-fourth  the 
light  that  it  would  if  placed  2|  inches  distant.  But  in  shortening 
the  focus  of  the  condenser  we  are  limited,  by  reason  of  its  neces- 
sary additional  thickness,  which  increases  its  liability  to  fracture, 
being  placed  nearer  to  the  light.  The  shorter  the  focal  length  of 
the  lens  the  thicker  it  must  be,  consequently  more  liable  to  come 
to  grief. 

Double  condensers  are  therefore  better  adapted  for  our  present 
requirements,  for  if  two  such  lenses  as  above  described  be  placed 
together,  the  focal  length  of  the  combination  is  reduced  one-half, 
so  that  a double  condenser  of  3 inches  focus  can  be  made  by 
placing  two  lenses  each  of  6 inches  focus  together.  As  such  lenses 
would  be  proportionately  thinner,  they  are  more  able  to  with- 
stand the  heat  to  which  they  are  sometimes  subjected. 


14 


THE  MAGIC  LANTERN  MANUAL. 


Different  arrangements  of  double  condensers  have  from  time  to 
time  been  tried,  with  the  object  of  taking  in  a greater  angle  of 
light,  and  of  being  as  free  from  spherical  and  chromatic  aberra- 
tion as  possible  (consistent  with  moderation  in  cost).  The  nearest 
combination  of  these  qualities  (all  of  which  are  a desideratum  in 
a good  condenser)  will  be  found  in  one  introduced  by  Sir  John 
Herschel  in  the  year  1821.  This  is  generally  considered  to  be 
about  the  best  double  condenser,  and  the  one  most  generally 
adopted  in  good  lanterns. 

It  consists  of  a meniscus  and  a bi-convex  lens  mounted  together, 
with  the  concave  side  of  the  meniscus  next  to  the  light  (see  Fig  2). 


In  purchasing,  notice  should  be  paid  to  this  point,  as  the  author 
has  several  times  found  in  lanterns  of  a supposed  first-class  cha- 
racter that  the  lenses  of  the  condensers  were  mounted  the  wrojig 
j way — viz.,  the  concave  side  nearest  the  picture,  and  the  bi-convex 
side  next  the  light.  How  this  should  have  happened  he  is  at  a 
loss  to  conceive,  unless  it  be  that  those  employed  in  putting  lanterns 
together  either  know  no  better  or  have  not  given  the  matter  con- 


Fig.  2. 


Fig.  3- 


CONDENSERS. 


15 


sideration.  He  was  much  surprised  a short  time  ago  to  receive 
from  a celebrated  maker  a pair  of  condensers  which  were  mounted 
the  wrong  way,  and  upon  inquiring  into  the  mistake,  the  reply  was 
that  the  lenses  were  in  the  positions  as  usually  supplied  to  the 
shops. 

Another  form  of  double  condenser,  which  has  been  extensively 
used  during  the  last  few  years,  consists  of  two  plano-convex  lenses, 
mounted  with  their  convex  sides  together,  almost  touching  (Fig.  3); 
and  although  for  all  ordinary  purposes  there  is  no  choice  between 
this  and  the  last  described,  yet  this  one  has  the  advantage  of  being 
produced  at  a somewhat  cheaper  rate.  As  a superior  condenser 
the  triple  form  carries  the  palm.  There  are  many  modifications  oi 
this  style,  the  first,  of  which  the  author  believes  was  constructed  by 
the  late  Mr.  Andrew  Ross,  in  1836 ; but  he  believes  the  most 
approved  to  be  that  recommended  by  Mr.  J.  Trail  Taylor,  in 
the  “British  Journal  Photographic  Almanac,”  1877,  consisting  e>t 
a pair  of  lenses  mounted  similar 
to  Herschel’s  arrangement,  with  a 
small  plano-convex  lens  interposed 
between  them  and  the  light,  as 
shown  in  Fig.  4.  By  this  arrange- 
ment the  focus  is  shortened,  and  a 
greater  angle  of  light  collected.  The 
introduction  of  a small  plano-con- 
vex lens  may  also  be  adapted  to  the 
double  plano-convex  form  (Fig.  3), 
and  it  was  by  the  use  of  this  arrange- 
ment some  years  ago  that  the  illuminating  power  of  the  old  lanterns 
at  the  B.oyal  Polytechnic,  with  large  long-focus  condensers,  was 
greatly  increased. 

Triple  condensers  are  often  used  in  lanterns  of  American  manu- 


1 6 


THE  MAGIC  LANTERN  MANUAL. 


facture  of  the  best  quality,  and  although  they  do  not  seem  to  be  so 
generally  adopted  in  this  country  as  they  merit,  the  author  has 
every  confidence  in  recommending  them  to  those  in  search  of  the 
best  condensers.  The  size  of  condenser  must,  to  some  extent,  be 
decided  by  the  size  of  picture  to  be  shown,  as  for  small  pictures  it 
is  useless  to  have  large  condensers,  throwing  rays  of  light,  only  a 
portion  of  which  are  transmitted  through  the  picture. 

In  the  days  of  hand-painted  slides,  which  were  usually  of  large 
size  (in  some  instances  as  much  as  6 inches  square  or  more),  con- 
densers of  equal  proportions  were  necessary  to  cover  them;  but 
now  that  photography  has  stepped  in,  we  are  able  to  produce  slides 
of  small  size  with  much  greater  delicacy  and  finer  detail  than  is 
possible  for  our  ablest  artists  to  produce  on  large  size  slides ; con- 
sequently, having  reduced  the  size  of  our  pictures,  we  may  propor- 
tionately reduce  the  size  of  our  condensers. 

Should  the  pictures  be  square  or  cushion-shaped  (the  case  in 
most  French  slides,  as  well  as  in  those  of  our  American  cousins, 
and  also  of  many  produced  by  the  Woodbury  process),  a condenser 
must  be  used  a little  larger  in  diameter  than  the  diagonal  distance 
across  the  picture ; but  with  slides  mounted  in  circles  (as  those  ot 
Mr.^YorkWmd^  others)  smaller  condensers  may  be  used.  For 
general  purposes,  the  author  has  concluded  that  condensers  having 
a diameter  of  4 inches,  and  a focus  of  2\  to  3 inches,  are  the 
most  useful  size,  this  diameter  being  large  enough  to  cover  the 
largest  photographic  slides  in  general  use. 

In  some  double  condensers  each  lens  is  made  of  different  quality 
of  glass,  and  this  has  misled  some  to  suppose  that  they  were  achro- 
matic. It  is  not  necessary  that  the  condensers  should  be  perfectly 
achromatic,  and  it  is  preferable  that  all  condenser  lenses  should 
be  composed  of  the  whitest  flint  glass. 

Although  a few  specks,  bubbles,  or  even  a scratch  or  two,  are 


OBJECTIVES. 


7 


not  very  detrimental  to  a condensers  performance,  such  would 
not  be  offered  by  any  optician  of  standing.  Let  care  be  taken 
that  the  lenses  do  not  fit  too  tightly  in  their  mounts,  so  as  to  allow 
for  expansion  by  heat  when  in  operation ; they  should  be  suffi- 
ciently slack  to  be  turned  round  in  their  cells  by  the  fingers. 

Before  using  the  condenser  it  is  advisable  to  warm  the  same 
before  the  fire  or  otherwise,  so  that  the  sudden  heat  when  the 
light  is  turned  up  may  not  fracture  it,  also  to  dispel  any  moisture 
that  may  accumulate  on  the  lenses.  An  outlet  for  this  moisture 
should  be  provided  in  the  centre  of  the  brass  ring  in  which  the 
lenses  are  mounted,  by  having  a few  holes  drilled  therein. 

OBJECTIVES. 

Having  fully  described  the  condenser  and  its  functions,  let  us 
now  consider  the  matter  of  the  Objective  Lens.  Its  duty  is,  to 
magnify  the  small  picture  previously  illuminated  by  aid  of  the 
condenser,  and  to  project  the  same  on  to  the  screen. 

The  qualities  desired  in  a Lantern  Objective  are  equal  defini- 
tion at  sides  and  centre  of  picture,  depth  of  focus,  freedom  from 
distortion  and  from  chromatism.  Although  it  is  of  importance  to 
adopt  condensers  of  good  construction  and  quality,  it  is  of  far 
greater  importance  that  good  object  glasses  be  used ; for,  with  a 
condenser  of  somewhat  inferior  quality,  and  a good  Objective,  a 
much  better  result  will  be  obtained  than  could  be  with  a good  con- 
denser and  an  inferior  Objective.  The  author  would  not,  there- 
fore, feel  justified  in  occupying  time  or  attention  in  describing  the 
worst  of  all  Objectives — a single  bi-con  vex  lens,  used  only  in  in- 
ferior or  toy  lanterns.  Better  than  this  are  two  plano-convex  lenses, 
mounted  with  the  convex  sides  together,  similar  to  the  condenser 
(Fig.  3) ; but,  to  get  anything  like  good  definition,  they  must  be 
of  long  focus ; and  in  “ second-rate  ” lanterns,  this  is  often  objected 


THE  MAGIC  LANTERN  MANUAL. 


18 

to,  they  being  principally  used  for  showing  comic  slips,  where  the 
larger  the  picture  the  better  appreciated  by  the  juveniles.  Some 
lanternists  pride  themselves  upon  the  large  size  of  disc  they  can 
show,  and  often  it  is  requi-red  to  exhibit  a picture  io  feet  in  dia- 
meter in  a distance  of  io  feet;  but,  as  short-focus  lenses  disperse 
the  rays  of  light  at  greater  angles,  inferior  definition  is  the  result, 
A short-focus  Objective,  which  has  found  favour  with  many,  con- 
sists of  a bi-convex  and  a meniscus  lens  mounted  together : the 
bi-convex  being  nearest  to  the  picture,  and  the  concave  side  of  the 
meniscus  outside,  or  farthest  from  the  picture,  with  a diaphragm 
a little  distance  in  front  of  it.  Although  giving  better  definition 
than  those  previously  mentioned,  the  small  diaphragm,  which  is 
necessary  to  give  sharpness  to  the  picture  alike  at  centre  with 
edges,  tends  to  diminish  the  illumination  on  the  screen. 

The  Photographic  Portrait  Combination  Lens  possesses  all  the 
requirements  necessary  in  a Lantern  Objective;  for  while  being- 
achromatic,  it  has,  if  of  moderately  good  quality,  sufficient  depth 
of  definition  and  flatness  of  field  to  satisfy  the  most  fastidious. 

These  lenses  have  received  the  careful  consideration  of  many 
of  our  ablest  opticians,  and,  by  reason  of  their  extensive  manufac- 
ture, they  can  be  procured  at  an  exceedingly  low  price. 

An  Achromatic  Portrait  Combination  is  made  by  Darlot,  and  also 
by  many  English  makers,  of  moderately  short  focus ; and  although 
the  front  lenses  are  of  less  diameter  than  the  back  combinations, 
the  screws  are  made  alike,  so  that  the  front  lenses  can  be  reversed, 
and  thereby  a long-focus  Objective  obtained,  which  in  many  in- 
stances proves  a great  convenience,  as  when  working  from  the 
back  of  an  audience  in  a large  room. 

It  must  be  remembered  that  when  working  with  the  single  long 
focus  lens  a diaphragm  should  be  used  in  front. 

In  the  best  lanterns  at  present  made  lenses  of  various  foci  are 


OBJECTIVES. 


19 


supplied,  usually  of  7^  9I,  and  12-inch  focus,  the  tubes  being 
telescopic  and  capable  of  extension  to  the  necessary  requirements 
of  the  lenses  used.  This  is  often  found  more  convenient  of  adap- 
tation to  the  various  sized  rooms  in  which  such  exhibitions  are 
conducted. 

For  his  own  choice,  the  author  much  prefers  to  see  a small, 
sharp,  bright  picture,  than  a large  one  of  inferior  definition  and 
illumination;  therefore,  for  this  reason,  would  recommend  the 
adoption  of  Objectives  of  long  foci,  whenever  it  may  be  prac- 
ticable. 

It  must  be  understood  that  the  smaller  the  picture  is  shown  the 
brighter  will  be  the  illumination,  for  “ light  decreases  inversely  as 
the  square  of  the  distance;”  thus,  a picture  shown  to  10  feet  in 
diameter  would  be  about  twice  as  well  illuminated  as  if  shown 
14  feet  diameter,  or  exactly  four  times  as  well  as  if  shown  20  feet 
in  diameter. 

An  approximate  rule,  which  will  be  found  useful  and  sufficiently 
correct  for  all  practical  purposes  when  it  is  necessary  to  determine 
the  lantern’s  distance  from  the  screen,  to  produce  a certain  disc 
with  a given  lens,  can  be  b6st  obtained  as  shown  by  the  formulas 
below : — 

Size  of  opening  in  slide  in  inches  = S 
Focus  of  Objective  in  inches  = F 

Lantern  distance  from  screen  in  feet  = L 
Diameter  of  disc  in  feet  = D 

T __  D x F,  p _L  x S,  p _L  x S, 

S F ~ D 

The  following  examples  will  probably  make  this  more  clear : — ■ 

Suppose  we  wish  to  find  the  distance  at  which  to  fix  the  lantern 
from  the  screen,  to  produce  a 15-feet  disc  with  a 6-inch  lens, 
using  a 3-inch  slide.  We  multiply  the  diameter  of  disc  D by  focus 


20 


THE  MAGIC  LANTERN  MANUAL. 


of  lens  F,  and  divide  by  size  of  slide  S,  which  will  give  us  the 
distance,  viz.,  30  feet. 

We  will  now  imagine  a case  where,  in  a certain  room,  we  must 
work  our  lanterns  from  a gallery,  or  upon  a screen  at  an  unalter- 
able distance,  possessing  only  one  lens  ; we  should  naturally  wish 
to  know  the  size  of  disc  we  could  produce.  To  arrive  at  this  we 
must  multiply  lantern  distance  from  screen  L by  size  of  picture 
S,  and  divide  by  focus  of  lens  F.  Another  illustration  will  complete 
our  series. 

As  in  the  previous  instance,  the  distance  at  which  we  can  work 
our  lanterns  from  the  screen  is  fixed,  and  also  the  diameter  of  the 
disc  is  a settled  matter,  and  we  wish  to  know  the  focus  of  the  lens 
it  will  be  necessary  to  use ; therefore,  by  multiplying  L by  S,  and 
dividing  by  D,  the  answer  will  give  the  focal  length  of  lens  required. 

Having  now  completed  our  survey,  and  described  the  optical 
portions  of  the  Magic  Lantern  and  their  respective  functions,  let 
us  now.  describe  and  illustrate  the  various  illuminating  powers 
applicable. 

The  simplest  form  of  these  is  the  little  ordinary  oil-lamp,  now 
only  used  in  toy  lanterns,  which  throw  a disc  of  2 to  4 feet,  for 
exhibiting  comic  slips. 

Superior  to  this  is  the  “Argand  Fountain  Lamp,”  with  concave 
silvered  reflector  (shown  at  Fig.  5),  in  which  circular  wicks  and 
the  best  sperm  or  colza  oil  can  be  used,  previously  camphorated. 
It  may  be  comphorated  by  adding  camphor,  previously  pounded 
in  a mortar,  with  a little  alcohol,  about  one  ounce  to  the  pint  of 
oil  being  sufficient.  It  has  been  recommended  to  soak  the  wicks 
in  strong  vinegar,  and  allow  them  to  dry  thoroughly  before  use,  as 
a preventive  against  charring. 

Reflectors  should  be  of  the  same  focal  length  as  the  condensers, 
the  illuminating  power  being  directly  midway  between  the  con- 


THE  SCI  OP  EICON. 


21 


denser  and  the  reflector.  Often  no  attention  is  paid  to  this  matter, 
the  result  being  that  the  reflector  is  worse  than  useless.  Glass  re- 
flectors, when  silvered  by  Liebig’s  process  (on  the  surface,  not 
behind),  are  much  superior  to  metal  ones.  We  must  not  omit  to 
mention  the  Argand  Burner,  in  which  house  gas  is  used  as  adapted 


Fig.  5.  Fig.  6. 


to  the  Magic  Lantern  (Fig.  6).  It  has  an  advantage  in  cleanli- 
ness, and  sometimes  in  convenience;  but  its  illuminating  power  is 
inferior  to  the  oil  lamp,  and  is  only  suitable  for  exhibiting  comic 
slips  on  small  screens.  The  “ Silber  Lamp,”  though  it  surpasses 
those  previously  mentioned  in  illuminating  power,  falls  far  behind 
that  of  the  “Sciopticon,”  which  it  will  be  now  our  duty  to  de- 
scribe. 


THE  SCIOPTICON. 

THE  name  of  this  instrument  is  equally  novel  as  is  its  whole 
construction,  when  compared  with  the  original  instrument. 
The  name  is  derived  from  two  Greek  words  signifying  “ Shadow 


22 


THE  MAGIC  LANTERN  MANUAL . 


View  ” or  “ Shadow  Picture.”  Its  inventor  is  Mr.  L.  Marcy,  of 
Philadelphia,  and  it  was  first  introduced  into  this  country  by  Mr. 
W.  B.  Woodbury,  who  thought  it  a fit  instrument  to  institute  as  a 
medium  between  the  old  oil  lantern  and  the  expensive  and  elabo- 
rate oxy-hydrogen  lantern. 

Its  chief  feature  is  its  lamp,  which  is  arranged  to  use  two  wicks, 
placed  edgewise  to  the  condenser,  and  in  which  paraffin  or  the 
best  crystal  oil  (camphorated  as  previously  explained,  but  in  less 
quantity)  may  be  used  to  produce  a light  far  surpassing  anything 
previously  seen  in  the  form  of  oil  lamps. 

Its  optical  portions  are  of  exceedingly  good  quality,  and  its 


Fig.  7. 


convenient  and  novel  form,  together  with  its  lightness  and  porta- 
bility, have  secured  for  it  an  unexceptionable  reputation.  Fig.  7 
shows  an  external  view  of  the  instrument,  and  Fig  8 is  a sectional 
view  of  the  same,  by  which  we  will  explain  its  various  parts. 

abc  and  d are  the  lenses  of  the  achromatic  objective,  e the 
milled  head  for  focussing,  f the  flange  of  the  objective,  by  which 
it  is  secured  to  the  ring  g,  which  is  made  of  wood,  for  the  con- 


THE  SCI OPTICON. 


23 


venience  of  changing  the  objectives  for  any  other  size  or  descrip- 
tion that  may  be  necessary  in  a special  case,  h and  h',  frame- 
work carrying  objective,  which  is  made  to  draw  in  or  out  to  suit 
the  focal  length  of  the  objective,  l,  portion  of  framework  forming 
base  of  the  instrument,  m and  n,  claw  and  flange,  by  which  the 
instrument  is  secured  to  the  top  of  a neat  packing-box,  with  which 
it  is  supplied,  o and  o',  stage  and  spring  for  the  reception  of  slides 
and  pictures : this  is  of  a most  convenient  form,  allowing  the  top 


Fig,  8. 


to  be  open  for  the  introduction  and  manipulation  of  chemical, 
photographic,  and  other  scientific  experiments,  p q,  the  condenser 
lenses,  4 inches  in  diameter,  and  of  short  focal  length,  mounted 
on  a very  approved  plan,  which  permits  of  either  lens  being  re- 


24 


THE  MAGIC  LANTERN  MANUAL. 


moved  from  its  cell,  s,  the  lamp  reservoir,  of  sufficient  capacity 
to  hold,  when  full,  enough  oil  for  four  hours’  entertainment.  It 
is  not  advisable  to  fill  this  reservoir  too  full,  and  care  should  be 
taken  not  to  allow  any  oil  to  get  outside,  in  which  case  an  unplea- 
sant smell  is  sometimes  produced,  u and  v,  tubes  carrying  i|-inch 
wicks,  each  of  which  are  disconnected  in  their  length,  thus  pre- 
venting the  transmission  of  heat  from  the  flame  to  the  oil-cham- 
ber, and  by  keeping  the  oil  quite  cool,  avoids  any  objectionable 
odour,  w w,  buttons  for  adjusting  the  wicks,  e e',  interior  of 
flame-chamber,  g g',  are  a pair  of  glasses  closing  the  ends  of  the 
flame-chamber;  their  liability  to  fracture  has  been  entirely  over- 
come by  using  toughened  glass,  h,  concave  silvered  reflector,  also 
used  to  close  the  back  of  the  instrument,  i and  j,  chimney  and 
cap,  which  are  made  telescopic,  and  can  be  taken  off  for  con- 
venience of  packing. 

The  merits  of  such  a powerful  oil  lantern  must  be  apparent  to 
all.  One  objection  has  been  raised  to  it,  namely,  that  of  a slight 
shadow  crossing  the  illuminated  disc,  in  a vertical  direction ; but 
this  is  of  so  little  consideration,  that  when  a picture  is  being 
shown  it  is  not  perceptible,  except  with  such  slides  as  show  a 
great  amount  of  sky,  and  in  this  case  it  can  be  reduced  to  a mini- 
mum by  a proper  attention  to  the  wicks.  Other  modifications  of 
double-wicked  lanterns  have  been  introduced,  but  it  cannot  be  said 
with  much  improvement.  One  of  these  was  to  contract  the  wicks 
at  the  front  ends,  and  to  expand  them  at  the  back,  to  obviate  the 
seeming  defect  of  the  dark  line  above  mentioned  ; but  after  con- 
siderable experience  with  one  of  this  class,  the  author  found  that 
by  this  placing  of  the  wicks  out  of  parallel,  the  flame  was  more 
likely  to  “fork”  and  the  wicks  to  burn  unevenly,  and  after  some 
time  a portion  of  the  illumination  was  sacrificed. 

Other  forms  of  both  double  and  triple-wicked  lamps  have  since 


i 


THE  SCIOPTICON. 


25 


been  introduced.  The  one  styled  the  “ Patent  Refulgent  Lamp  ” 
is  constructed  both  with  double  and  triple  wicks,  and  possesses 
merits  in  many  ways,  which  go  to  prove  its  excellence. 

Since  the  introduction  of  the  Sciopticon,  many  improvements 
have  been  made  by  the  Sciopticon  company  and  other  firms.  The 
lamps  are  now  made  detached  from  the  body  of  the  lantern,  and 
in  the  new  Sciopticon  Lamp  a circular  glass  is  used  at  each  end 
of  the  flame-chamber,  they  having  been  found  to  withstand  the 
heat  better  by  reason  of  their  equal  expansion  and  contraction, 
and  their  liability  to  break  thereby  considerably  reduced. 

One  of  the  valuable  improvements  of  Mr.  Newton  was  the 


Fig  9.  Fig.  IO. 


introduction  of  a hinged-silvered  reflector,  closing  the  back  end  of 
the  flame  chamber.  In  the  centre  of  this  reflector  is  a small, 
blue  glass  window,  through  which  the  flame  may  be  viewed  to 
adjust  the  flames  (see  Figs.  9 and  10). 

Various  other  forms  of  oil-burning  lamps  are  now  in  the  market 
some  with  three  and  four,  and  another  with  five  wicks.  One 
styled  the  “ Pamphongos  ” is  stated  to  give  a very  superior  light ; 
but  the  writer’s  recent  experience  with  one  of  the  most  modern 


26 


THE  MAGIC  LANTERN  MANUAL. 


5-wick  lamps  brings  him  to  conclude  that  the  extreme  delicacy 
and  attention  necessary  in  the  adjustment  of  the  wicks  to  pre- 
vent smoking  and  the  great  amount  of  heat  emitted  are  serious 
drawbacks. 

The  Sciopticon,  and  most  other  oil-burning  lanterns,  are  now 
adapted  so  that  limelight  can  be  introduced.  Having  now  com- 
pleted our  review  of  the  family  of  oil- 
burning lanterns,  it  may  be  well,  before 
entering  into  a description  of  the  Oxy- 
Hydrogen  Limelight,  to  allude  to  other 
lights  which  have  from  time  to  time  been 
tried  with  more  or  less  success. 

The  Pyro  - Hydrogen  Lamp  (Fig.  n) 
was  some  few  years  ago  introduced  into 
this  country  from  Germany  by  Mr. 
Walter  B.  Woodbury.  The  light  was 
produced  by  a jet  of  heated  air  blowing 
at  a high  pressure  through  a flame  of 
hydrogen,  and  projected  upon  a disc  of 
lime.  The  light  was  inferior  to  the  oxy- 
hydrogen  in  its  poorest  form,  and  the  trouble  nearly  the  same,  and 
has  for  the  present  fallen  into  disuse.  No  doubt  the  idea  will,  at 
some  future  time,  receive  further  attention,  and  may  possibly 
develope  into  a more  practical  means  of  illumination. 


Fig.  11. 


THE  MAGNESIUM  LANTERN. 


2? 


THE  MAGNESIUM  LANTERN. 

AS  an  illuminating  power  the  combustion  of  the  metal  mag- 
nesium must  not  be  omitted.  As  adapted  to  the  Magic 
Lantern  its  success  has  been  limited,  principally  owing  to  the  un- 
steadiness of  the  light,  and  to  the  necessity  of  providing  a long 


Fig.  12. 


chimney  to  carry  away  the  great  amount  of  magnesia  vapour,  the 
result  of  the  combustion.  For  these  and  other  reasons  it  is  not 
used  for  Magic  Lanterns  generally,  but  may  be  adopted  in  the 
case  of  a lecturer  or  experimentalist  wishing,  during  his  lecture,  to 
show  an  occasional  diagram.  The  most  practical  apparatus  of 
this  kind  is,  perhaps,  that  manufactured  by  Mr.  Solomon,  con- 

3 


28 


THE  MAGIC  LANTERN  MANUAL. 


structed  to  burn  the  metal  in  ribbon  or  wire  form,  and  is  fitted 
with  an  ingenious  clockwork  arrangement  for  self-feeding.  The 
arrangement  of  lamp  and  lanterns  are  clearly  shown  at  Fig.  12. 

Besides  the  aforenamed  lamp,  there  was,  some  years  ago, 
another  in  the  market,  invented  by  a Mr.  Larkin,  constructed  to 
burn  the  magnesium  in  the  form  of  a powder,  which  was  obtained 
at  a much  cheaper  rate.  And  although  this  lamp  possessed  very 
great  merit,  it  was  probably  abandoned  before  being  brought  to  a 
practical  issue,  and  it  must  be  regretted  that  such  a beautifully 
actinic  and  powerful  light  as  magnesium  has  not  been  yet  brought 
into  more  general  use,  and,  for  anyone  having  the  time  and  oppor- 
tunity to  devote  to  its  serious  consideration,  there  is  a field  open  here 
for  bringing  to  the  aid  of  the  lantern  what  must  always  be  regarded 
as  a most  valuable  adjunct.  Probably  the  present  high  price  of 
magnesium  has  precluded  the  introduction  of  other  appliances  for 
its  combustion,  but  no  doubt  this  would  be  materially  altered  by 
the  application  of  such  a method  as  would  bring  magnesium  into 
greater  demand. 


ITHIN  the  last  few  years  the  Electric  Light  has  been 


applied  to  the  lantern  in  a variety  of  forms,  with  more  or 
less  success.  In  the  best  forms  the  light  is  superior  to  the  lime 
light,  but  its  unsteadiness,  and  the  great  liability  of  the  lamps  not 
working,  and  its  cost  of  maintenance,  has  placed  it  far  behind  the 
lime  light  for  general  purposes.  In  such  institutions  as  the 
Victoria  University  (Owen’s  College),  Manchester,  under  the  able 
management  and  superintendence  of  Sir  Henry  Roscoe,  it  is  used 
chiefly  for  scientific  demonstrations  and  research. 


THE  ELECTRIC  LIGHT 


THE  LIME  LIGHT. 


29 


THE  LIME  LIGHT, 


HE  “ Lime.  Light,”  or,  as  it  is  sometimes  styled,  the  “ Drum- 


mond Light,”  has  been  in  use  as  far  back  as  the  year  1820. 
It  consists  of  a jet  of  oxygen  blown  through  a flame  of  hydrogen 
on  to  a piece  of  lime,  which  latter  is  rendered  so  extremely  in- 
candescent, that  a light  is  obtained  superior  in  importance  to  any, 
the  electric  excepted.  Sometimes  the  flame  of  a spirit  lamp  is 
substituted  for  that  of  the  hydrogen;  it  is  then  known  as  the 
“ Oxy-Calcium  Lime  Light.”  Before  proceeding  to  enter  upon 
the  different  methods  of  using  the  gases,  it  will  perhaps  be  as  well 
to  explain  the  mode  of  their  manufacture. 


Where  the  manufacure  of  oxygen  gas,  not  only  for  illuminating 
purposes,  but  for  sanitary  purposes  also,  is  conducted  on  a large 
scale  commercially,  the  method  of  M.  Tessie  de  Motay  is  usually 
adopted.  Briefly  described,  it  consists  in  heating  in  a large  retort 
manganate  of  soda,  and  blowing  through  it  high-pressure  steam, 
which  carries  with  it  the  oxygen  contained  in  the  manganate  of 
soda.  After  all  the  gas  has  been  extracted,  the  steam  is  shut  off, 
and  air  is  introduced  to  the  retort,  which  restores  to  the  manganate 
of  soda  the  oxygen  in  place  of  that  which  had  been  extracted.  It 
is  then  subjected  again  to  the  steam  jet,  and  so  on  with  steam  and 
air  alternately,  the  manganate  of  soda  being  always  replenished 
with  oxygen  on  the  admission  of  the  atmosphere.  A large  manu- 
factory on  this  principle  was  established  at  Brussels,  as  also  in 
many  of  the  large  cities  in  America,  where  oxygen  gas  i»  produced 
as  cheaply  as  25 s.  per  1,000  cubic  feet. 

In  England  the  making  of  oxygen  gas  is  usually  conducted  on 


OXYGEN  GAS. 


30 


THE  MAGIC  LANTERN  MANUAL. 


a small  scale,  consumers  having  generally  to  prepare  their  own ; 
but  it  is  to  be  hoped  that  ere  long  we  may  be  blessed  with  similar 
advantages,  and  have  the  opportunity  of  purchasing  oxygen  gas 
at  a rate  somewhat  proportional  with  that  of  house  gas.  There 
are  various  other  methods  of  producing  oxygen  gas  than  the  one 
above  described,  but  as  our  object  in  this  treatise  is  to  produce  in 
quantities  suitable  for  lantern  requirements,  it  is  only  necessary  to 
speak  of  the  most  practical  and  economical  methods  of  arriving 
at  this  result. 

From  one  pound  of  chlorate  of  potash  in  the  form  of  crystals  or 
powder,  to  which  one-third  of  a pound  of  black  oxide  of  manganese 
has  been  added,  together  heated  in  a retort,  four  cubic  feet  of 
oxygen  gas  may  be  obtained,  although  theoretically  there  should 
be  more.  The  exact  proportion  of  this  mixture  is  not  of  import- 
ance, as  the  manganese  undergoes  no  chemical  change  under  the 
operation,  the  oxygen  being  wholly  derived  from  the  chlorate  of 
potash,  which,  if  used  alone,  would  liquefy  on  the  application  of 
heat,  and  give  off  the  gas  so  quickly  as  to  be  ungovernable.  The 
addition  of  the  manganese  is  merely  to  separate  the  particles  of 
the  chlorate,  so  that  the  gas  when  given  off  may  be  more  under 
control ; also  by  its  addition  less  temperature  is  required.  After 
all  the  oxygen  has  been  given  off,  the  residue  is  chloride  of  potas- 
sium and  oxide  of  manganese  : the  former  being  soluble  in  water, 
may  be  separated  from  the  latter  by  decantation,  and  after  drying 
may  be  used  again  and  again  with  an  assurance  of  its  purity. 
The  greatest  care  must  be  exercised  in  the  purchase  of  these 
chemical  ingredients,  as  the  introduction  of  any  organic  matter 
into  the  retort  on  heating,  the  same  would  ignite,  and  a serious 
explosion  would  be  the  inevitable  result.  Some  years  ago  an 
acquaintance  of  the  writer’s,  who  in  the  exercise  of  his  profession 
had  made  this  gas  a thousand  times,  one  day  upon  being  called 


THE  LIME  LIGHT 


31 


upon  for  a bag  of  gas,  found  his  stock  of  manganese  exhausted,  he 
therefore  sent  out  to  a neighbouring  chemist’s  shop  for  a supply. 
By  some  means  the  manganese  had  been  accidently  mixed  with 
soot,  which  in  appearance  it  somewhat  resembles,  and  on  using 
some  a fatal  accident  resulted.  Although  it  is  very  rarely  that 
manganese  is  intentionally  adulterated,  it  is  well  to  be  on  the  safe 
side,  and  safety  from  such  accidents  as  the  one  alluded  to  may  be 
obtained  by  heating  the  manganese  to  redness  in  a crucible  before 
mixing  it  with  the  chlorate  of  potash.  This  is  a simple  matter, 
and  should  be  done  with  every  fresh  sample.  By  reason  of  its 
small  cost  it  may  be  purchased  in  sufficient  quantity  to  last  a 
season.  (Chlorate  of  potash  can  be  purchased  at  from  7 d.  to  gd. 
per  lb.,  and  manganese  at  2d.  per  lb.)  Care  must  also  be  taken 
that  no  deleterious  substance  enters  during  the  roasting.  If  desired, 
fine  sand  may  be  substituted  instead  of  manganese,  but  it  must 
be  previously  rid  of  any  organic  matter. 

Retorts  best  suited  to  oxygen-making  are  those  made  of  sheet 
iron,  conical  in  shape  and  brazed  together,  having  a dish  bot- 
tom and  a brass  top,  on  to  which  latter  is  attached  by  screws  a 
loose  brass  cap  with  a piece  of  bent  wrought  iron  tube  screwed 
therein. 

As  a medium  for  making  the  joint  between  the  retort  and  the 
cap,  the  writer  advocates  “ asbestos,”  which  is  very  durable  and 
effective. 

The  gas  in  passing  from  the  retort  (if  to  be  stored  in  a bag) 
should  pass  through  a wash-bottle,  sometimes  called  a “ cooler  ” 
or  “ purifier,”  consisting  of  a “ WoulfFs  Bottle  ” partly  filled  with 
water.  The  tube  connecting  the  retort  with  the  wash-bottle  may 
be  partly  of  lead  and  partly  of  india-rubber,  the  leaden  portion 
being  of  sufficient  length  to  reach  nearly  to  the  bottom  of  the 
bottle,  and  should  be  perforated  with  small  holes  at  some  dis- 


32 


THE  MAGIC  LANTERN  MANUAL. 


tance  from  its  end,  thus  forming  a rose-head.  The  gas  in  passing 
through  the  water  will  be  purified,  cooled,  and  rid  of  any  particles 
of  manganese,  which  are  sometimes  carried  away  with  the  gas  from 
the  retort,  and  which  are  apt  to  choke  the  nozzles  of  the  jet  if  the 
washing  be  omitted.  The  outlet-pipe  should  be  a bent  tube  long 


Fig.  13. 


enough  to  enter  the  bottle,  and  sufficient  in  length  to  connect  with 
the  gas-bag.  The  whole  arrangement  is  illustrated  at  Fig.  13. 

The  retort  may  be  heated  on  a fire,  or  by  gas,  which  latter  is 
preferable,  a large  Bunsen  burner  being  placed  in  the  conical 
stand,  which  is  of  sheet  iron,  and  forms  a support  for  the  retort. 
The  Bunsen  burner  has  been  shown  out  of  position  to  illustrate 
the  kind  adopted.  Though  this  is  a matter  upon  which  the  reader 
may  use  his  own  discretion,  many  of  the  burners,  made  by  Mr. 
Thomas  Fletcher,  of  Warrington,  for  cooking  and  other  uses, 
being  admirably  suited  to  the  purpose. 


THE  LIME  LIGHT. 


33 


So  soon  as  the  gas  has  been  given  off  (which  may  be  noticed 
by  the  cessation  of  bubbling  in  the  wash-bottle),  the  tube  con- 
necting the  retort  with  the  wash-bottle  should  be  disconnected ; if 
this  be  neglected,  and  the  heat 
from  the  retort  withdrawn,  a 
vacuum  will  be  caused  on 
cooling,  which  may  draw  the 
water  from  the  wash-bottle  into 
the  retort,  and  a miniature 
boiler  explosion  will  very  likely 
be  the  result.  To  obviate  this, 
an  empty  bottle  may  be  placed 
in  the  tube  between  retort  and 
wash-bottle ; thus  in  the  case 
of  a vacuum  being  created,  the  water  in  the  wash-bottle  would  be 
simply  drawn  as  far  as  the  empty  bottle,  without  proceeding 
farther  (see  Fig.  14). 

It  may  be  well  here  to  remark  that  before  proceeding  to  fill  a 
bag  with  either  oxygen  or  hydrogen,  it  should  be  warmed  to  soften 
it ; and  any  old  gas  it  may  contain  should  be  expelled  by  folding 
and  rolling  up  the  bag. 

HYDROGEN  GAS. 

It  is  beyond  doubt  that  pure  hydrogen  is  superior,  in 
illumination,  as  compared  with  house  gas  (carburetted  hydrogen). 
Not  only  is  less  of  it  required,  but  also  less  oxygen  to  produce 
an  equal  result,  though  the  trouble  of  making  it  does  not  always 
repay  the  advantages  gained.  In  most  large  towns  in  this 
country  a fair  pressure  of  house  gas  can  be  had,  and  for  ordi- 
nary lantern  exhibitions  this  is  used  direct  from  the  main  in 
what  is  called  a “safety”  or  “blow-through  jet.”  When  the 


Fig.  14. 


34 


THE  MAGIC  LANTERN  MANUAL. 


pressure  is  feeble,  as  it  usually  is  in  small  towns,  it  is  custo- 
mary to  fill  a gas-bag  from  the  main,  and  to  use  it  under  pressure, 
in  the  same  way  as  the  oxygen.  Hydrogen  gas  is  produced  by 
the  action  of  dilute  sulphuric  acid  upon  zinc;  the  gas  being 
liberated  and  sulphate  of  zinc  being  deposited.  At  Fig.  15  is 


Eg'  15* 


shown  a general  arrangement  for  the  purpose  of  making  this  gas. 
It  consists  of  a glass  bottle,  with  a good  tight-fitting  cork,  and  a 
funnel-top  tube  extending  nearly  to  the  bottom  of  the  bottle, 
through  which  the  sulphuric  acid  and  water  (in  the  proportion  of 
6 of  water  to  1 of  acid)  are  poured,  and  thus  brought  into  contact 
with  granulated  or  clean  zinc  cuttings  lying  at  the  bottom  of  the 
bottle.  The  gas  should  be  allowed  to  blow  through  for  a short 
time  to  get  rid  of  the  air  contained  in  the  bottle  at  starting,  and 
then  may  be  collected  by  the  bent  tube  from  the  upper  portion  of 


THE  LIME  LIGHT, 


35 


the  vessel.  If  the  gas  is  to  be  used  from  a bag,  it  should  be 
washed  in  like  manner  as  the  oxygen,  as  shown  in  the  em 
graving. 

Dobereiner’s  Lamp  (Fig.  16)  is  an  automatic  hydrogen  genera- 
tor, and  may  be  made  of  large  size  if  re- 
quired. A is  a glass  cylinder  containing  a 
very  dilute  solution  of  sulphuric  acid ; z is 
a small  block  of  zinc  suspended  by  a lead 
wire  inside  the  glass  funnel  f,  which  is 
cemented  to  the  top  e,  and  closed  by  the 
stop-cock  c.  By  action  of  the  acid  upon 
the  zinc,  f is  soon  filled  up  with  gas,  dis- 
placing the  solution,  which  is  driven  into  A, 
and  thereby  stopping  the  action.  As  soon 
as  the  stop-cock  is  opened  the  hydrogen  is 
liberated,  through  a jet,  on  to  a piece  of 
spongy  platinum,  which  produces  a light. 

As  the  hydrogen  is  liberated  the  solution  will  rise  in  f,  and  the 
action  is  immediately  renewed  between  the  acid  and  the  zinc,  and 
continues  so  long  as  the  stop-cock  remains  open. 

Many  modifications  of  this  apparatus  have  been  devised:  one 
by  the  author  is  illustrated  at  Fig.  17.  It  was  constructed  of  two 
large  earthenware  jars,  the  top  jar  having  the  bottom  cut  out,  and  it 
was  fixed  in  an  inverted  position  over  the  bottom  one  by  a good 
deep  india-rubber  stopper,  made  of  a block  of  india-rubber,  fitting 
each  jar-mouth  tightly,  and  through  which  a lead  tube  passed  to 
the  bottom  of  the  under  jar.  Upon  this  lead  tube  was  fixed  a 
cylinder  of  zinc.  The  outlet  pipe  was  also  a leaden  tube  secured 
into  the  india-rubber  stopper.  The  apparatus  was  charged  by  fill- 
ing the  bottom  jar  with  sulphuric  acid  one  part,  and  water  six  01- 
seven  parts ; then  by  connecting  the  upper  jar  the  gas  was  quickly 


36  THE  MAGIC  LANTERN  MANUAL. 

generated,  and  the  liquid  forced  up  the  leaden  tube  into  the  upper 
jar.  A steady  pressure  could  be  maintained  with  this  apparatus, 


Fig.  17. 

which  was  wholly  enclosed  in  a neat  wooden  box  with  a loose 
top  and  front. 

LIMES. 

Limes  for  use  with  the  oxy-hydrogen  light  may  be  purchased  in 
two  forms  and  of  two  kinds  and  qualities — namely,  discs  and 


THE  LIME  LIGHT 


37 


cylinders,  hard  and  soft,  and  good  and  bad.  Shape  is  of  little 
importance ; the  one  most  in  general  use  and  perhaps  most  con- 
venient is  cylindrical,  about  i inch  in  diameter  and  i\  inches  long, 
perforated  in  their  entire  length  with  a hole  t3q  inch  in  diameter  to 
fix  them  on  to  the  lime-pin  of  the  jet.  Discs  are  made  of  two 
sizes,  if  and  2\  inches  in  diameter.  Hard  limes  are  found  best 
suited  for  the  oxy-hydrogen  and  high  pressures,  soft  ones  being 
best  for  oxy-calcium  and  low  pressures.  Those  known  to  opticians 
as  “ Excelsiors  ” are  perhaps  the  best  in  the  market,  and  answer 
well  for  any  form  of  Lime  Light. 

As  lime  has  a powerful  affinity  for  moisture,  and  will  not  keep 
intact  if  exposed  to  the  atmosphere,  it  is  necessary  to  wrap  them 
in  tinfoil  after  they  are  made,  and  pack  them  in  an  air-tight  box 
or  bottle  large  enough  to  contain  a dozen.  An  excellent  plan  for 
preservation  is  to  dip  them  in  a solution  of  india-rubber  in  benzole. 

In  whatever  form  the  limes  are  preserved,  as  a preventive  from 
splitting  when  the  oxygen  is  turned  on,  they  should  be  thoroughly 
dried  before  use.  A good  plan  is,  upon  taking  them  from  their 
box,  to  place  them  in  the  oven  or  on  the  top  bar  of  the  fire-grate 
until  they  are  quite  hot. 

It  is  not  an  unfrequent  occurrence,  and  one  not  a little  annoying, 
to  find  upon  opening  a box  of  limes  that  moisture  has  gained 
admittance,  and  that  the  limes  are  slacked  and  worthless.  Many 
substitutes  for  lime  have  been  tried  with  more  or  less  success ; the 
best  of  these  which  has  come  under  the  author’s  notice  being  the 
oxide  of  zirconium,  which  is  described  by  Du  Mothay  as  “the 
most  infusible,  unalterable,  and  the  most  luminous  substance  at 
present  known.” 

Many  years  ago  the  author  purchased  an  oxy-hydrogen  lamp  of 
French  manufacture,  in  which  a small  piece  of  oxide  of  zirconium 
was  used  instead  of  lime,  but  he  found  that  it  was  not  so  imperish- 


38 


THE  MAGIC  LANTERN  MANUAL. 


able  as  it  had  been  represented.  By  the  continuous  action  of  the 
oxy-hydrogen  flame  for  a few  hours  it  decreased  materially  in  size; 
however,  it  was  a step  in  the  right  direction. 

Artificial  limes  have  previously  been  described  and  made  by 
many  lanternists,  and  to  this  subject  the  writer  has  devoted  con- 
siderable time  and  expense,  with  the  object  of  producing  an 
efficient  substitute  for  the  crude  lime;  and  within  the  last  few 
months  has  renewed  his  research  in  this  direction,  conjointly  with 
Mr.  Lewis  Wright,  subjecting  zirconium  and  other  substances  to 
a pressure  of  90  tons  to  the  square  inch,  and,  though  the  results  of 
these  experiments  have  not  been  thoroughly  successful,  it  is  hoped 
at  some  future  time  these  and  similar  experiments  may  be  re- 
newed, trusting  to  find,  at  all . events,  a better  substitute  for  lime 
than  that  with  which  we  are  at  present  acquainted. 

It  is  as  well  to  possess  a few  artificial  limes  in  case  of  emergency, 
and  for  the  lecturer  who  may  only  require  a light  occasionally, 
perhaps  the  best  for  such  a purpose  is  made  of 

Precipitated  chalk 8 parts. 

Carbonate  of  magnesia  (ponderous)  . 1 „ 

mixed  together,  with  the  addition  of  a little  very  thin  gum  water, 
and  subjected  to  a good  pressure. 

In  preference  to  purchasing,  many  make  their  own  limes,  which 
can  be  done  from  a block  of  unslaked  lime,  to  be  obtained  at 
almost  any  town  in  the  kingdom. 

GAS-BAGS. 

These  have  been  the  receptacles  in  most  general  use  for  the 
gases  used  in  lime-light  effects.  They  are  made  of  mackintosh 
cloth  in  the  form  of  a wedge,  and  of  two  qualities,  the  best  being 
made  of  three  thicknesses  of  cloth,  with  india-rubber  inserted,  of 
black  material  generally,  and  are  in  the  end  by  far  the  cheapest 


THE  LIME  LIGHT. 


39 


and  most  serviceable.  When  out  of  use,  all  the  old  gas  should  be 
expelled,  and  may  be  folded  up  and  put  away.  Sometimes  they 
are  liable  to  become  somewhat  stiff ; this  can  easily  be  removed 
by  warming  for  a short  time  before  a fire  or  placing  them  for  an 
hour  so  in  a warm  room. 

For  those  who  may  by  accident  chance  to  have  a leaky  gas-bag, 
it  is  well  to  mention  an  excellent  remedy,  which  in  all  cases  of 
emergency  will  prove  effectual.  This  is  a piece  of  common  sticking- 
plaster  made  hot  and  applied.  The  author  has  known  this  method 


Fig.  1 8. 


to  be  used  in  cases  where  india-rubber  solution  has  been  out  of 
reach,  and  it  has  answered  admirably  until  a better  remedy  could 
be  applied. 

When  both  a bag  for  oxygen  and  one  for  hydrogen  are  used, 
they  must  be  kept  for  their  own  respective  gases,  and  not  inter- 
changed, each  being  marked  O or  H to  signify  their  contents;  there- 
fore, whenever  a bag  is  to  be  filled,  all  old  gas  and  air  should  be 
expelled  by  folding  the  bag  with  the  tap  open,  and  before  unfolding 
the  bag  the  tap  should  be  closed,  to  prevent  any  air  being  sucked 


40 


THE  MAGIC  LANTERN  MANUAL. 


back.  As  soon  as  the  connections  are  made  the  tap  can  be 
opened.  When  bags  have  to  be  transported  or  sent  by  rail,  it  is  a 
good  plan  to  have  a loose  outer  covering  of  canvas  or  similar 
material. 

PRESSURE  BOARDS 

Are  necessary  with  gas-bags,  to  form  a means  of  applying  weights. 
They  consist  of  two  boards  hinged  together  at  one  end,  with  a 
semicircular  hole  cut  in  same  end  to  allow  the  pipe  and  tap  to 
project.  A hinged  shelf  is  usually  fixed  on  the  top  board,  upon 
which  the  weights  are  placed  (see  Fig.  18).  This  is  the  best  form 
of  pressure  board,  being  a lever,  with  the  fulcrum  at  the  hinges. 


Fig.  19. 


Sometimes  a single  board  is  used,  which  is  fixed  by  hooks  placed 
in  the  floor  at  the  lower  end  of  the  board. 

When  using  both  oxygen  and  hydrogen  from  gas-bags  it  is  of 


THE  LIME  LIGHT. 


41 


the  utmost  importance  to  have  the  pressures  equal.  With  this  ob- 
ject a pressure  frame  has  been  devised  to  contain  two  bags,  which 
latter  must  be  the  equal  size  on  the  surface  presented  to  the  pres- 
sure frame,  though  it  is  not  necessary  that  they  should  be  of  equal 
depth ; thus  the  hydrogen  bag  may  be  deeper  in  the  wedge  form 
than  the  Oxygen  bag,  seeing  that  more  of  the  hydrogen  is  used. 

Only  one  set  of  weights  are  required,  and  if  the  above  precau- 
tions have  been  attended  to,  the  pressure  on  both  bags  will  be 
alike,  as  will  be  seen  bf  Fig  19.  This  frame  is  composed  of 
wood,  with  canvas  inserted,  and  by  straps  at  the  back  the  bags 
are  prevented  from  slipping.  Weights  are  rarely  ever  included  in 
a travelling  lanternist’s  outfit,  being  generally  obtainable  in  some 
form  or  other  everywhere. 

The  weight  necessary  to  give  sufficient  pressure  on  large  bags 
for  oxy-hydrogen  mixed  gases  is  as  much  as  two  hundredweight 
and  sometimes  more,  but  with  safety  jets  and  oxy-calcium  half  this 
amount  is  usually  sufficient.  Although  the  method  of  gas-bags 
and  pressure  boards  is  excellent  so  far  as  portability  goes,  it  has 
the  failing  of  inconstancy  of  pressure,  also  the  wear  and  tear  is 
great.  For  fixed  or  permanent  use,  gas-holders  are  highly  prefer- 
able. 

INDIA-RUBBER  TUBES. 

The  best  quality  are  those  of  a red  colour,  and  when  cost  is  not 
considered,  those  of  extra  thickness  of  walls  are  most  suitable,  as 
they  do  not  so  suddenly  bend  or  kink,  and  close  the  passage.  The 
author  purchased  some  of  this  class,  which  it  is  almost  impossible 
to  block  up  in  the  passage  by  bending.  Large-bore  tubes  are 
preferable  to  the  small-bore  ones  we  see  so  generally  used,  and  if 
of  any  great  length,  should  be  at  least  \ inch  internal  diameter. 
It  is  astonishing  how  small  a reduction  in  the  passage  will  reduce 
the  pressure  considerably.  Tubes  should  not  be  used  that  are  in- 


42 


THE  MAGIC  LANTERN  MANUAL. 


ternally  lapped  with  iron  wire,  as  the  wire  reduces  the  pressure  by 
friction.  In  the  coupling  of  tubes,  see  that  the  couplings  are  as 
large  in  the  bore  as  the  tube : often  this  is  not  the  case,  but  the 
coupling  is  the  same  diameter  outside  as  the  tube  is  inside.  An 
easy  method  of  coupling  is  to  turn  the  tube  inside  out  for  an  inch 
or  so,  then  insert  the  coupling  and  pull  the  tube  back  again  to  its 
original  form. 

All  taps  should  be  looked  to,  to  see  that  there  is  a full  and  free 
passage  through  them,  as  not  unfrequently  the  plug  is  bored  with 
a hole  not  one-half  the  area  of  the  tube.  It  is,  therefore,  always 
desirable  to  use  taps  of  a size  larger,  with  the  plugs  well  cleaned 
out  and  lubricated  with  tallow. 

GAS-HOLDERS. 

Where  the  lime  light  is  often  required  in  one  fixed  place,  gas- 
holders claim  many  advantages  over  gas-bags.  No  wash-bottles  are 
required ; the  gas  does  not  deteriorate  in  quality  by  being  stored ; 
and,  if  properly  constructed,  one  even  pressure  can  be  maintained ; 
none  of  which  advantages  are  to  be  derived  from  gas-bags  and 
pressure  boards.  Gas-holders  are  sometimes  made  of  zinc,  but 
more  frequently  of  iron.  A friend  of  the  author’s  has  a very  good 
and  useful  one  fixed  in  his  garden,  and  made  of  two  casks,  the 
outer  one  being  sunk  into  the  ground,  and  the  inner  one  inverted, 
forming  the  holder.  For  a cheap  article  this  is  a very  effective 
one,  although  not  very  elegant  in  appearance. 

The  best  gas-holders  that  have  come  under  the  author’s  notice 
were  two  constructed  for  a friend.  They  were  made  in  shape 
similar  to  a small  dish-end  steam  boiler,  of  wrought  iron  plates 
F-inch  thick,  well  riveted  together.  A man-hole  was  cut,  and  a 
cover  for  same  attached  (as  in  a steam  boiler),  by  which  a boy 
could  get  inside  to  clean  out  and  paint  when  necessary.  A cut 


THE  LIME  LIGHT 


43 


of  same  will  be  seen  at  Fig.  20.  The  pressure  was  applied  by 
water  from  a cistern,  and  conveyed  to  the  inside  of  the  holder 
by  the  pipe  p.  The  end  of  this  pipe  was  covered  with  a small 
quantity  of  water  placed  in  a cup,  open  at  the  top,  and  from  this 
cup  another  pipe  takes  the  overflow  to  the  bottom  of  the  holder, 
so  as  to  avoid  the  splashing  and  noise.  The  amount  of  pressure 
is  regulated  by  the  distance  between  the  surface  of  the  water  in 


Fig.  20. 


the  cistern  c,  and  the  surface  of  the  water  in  the  cup  inside  the 
holder.  No  matter  how  much  or  how  little  gas  be  in  the  holder, 
the  pressure  is  always  uniform.  The  pressure  can  be  increased  or 
decreased  by  increasing  or  decreasing  the  distance  between  the 
two  surfaces  of  the  water,  as  before  stated.  G is  the  gas  outlet, 
1 is  the  inlet,  w is  the  pipe  to  empty  the  holder  when  filling  with 
gas.  For  a fixed  apparatus,  this  one,  perhaps,  presents  the  best 
advantages. 


4 


44 


THE  MAGIC  LANTERN  MANUAL. 


Portable  gas-holders  have  also  had  the  careful  consideration  of 
scientific  men,  and  at  Fig.  21  will  be  seen  an  excellent  form  of 


Fig.  22. 

portable  gas-holder,  de- 
signed by  Mr.  S.  Highley, 
which  was  exhibited  by 
him  in  the  Exhibition  of 
1862,  and  is  described  by 
him  thus : — 

“This  I originally  de- 
signed for  a professor’s 
lecture-room,  where  only 
small  quantities  of  oxygen 
were  required  at  a time, 
for  the  display  of  an  occa- 
sional diagram  in  illustrat- 
ing a course  of  lectures, 
and  to  avoid  the  daily  and  frequent  production  of  oxygen.  Fig.  22 
shows  how  I contrived  this  arrangement,  so  that  the  lantern  could  be 


Fig.  21. 


THE  LIME  LIGHT, 


45 


packed  in  the  body  of  the  gasometer  for  travelling,  if  necessary.” 
When  unpacked  and  arranged  as  in  Fig.  21,  it  will  be  seen  that 
the  “ bell  ” which  holds  the  gas  is  square,  instead  of  cylindrical, 


Fig.  24. 

and  slides  into  a double 
casing,  shown  in  section 
(Fig.  22),  that  is  filled  with 
water,  so  as  to  form  an  air- 
tight water-joint  for  the  run 
of  the  bell,  and  to  reduce 
the  bulk  of  the  water  re- 
Fig.  23.  quired  to  a minimum.  It 

was  also  designed  as  a stand 
for  the  lantern  as  shown.  Although  this  apparatus  was  well  ad- 
apted for  the  lecturer,  experimentalist,  or  photographer,  it  was  of 
insufficient  capacity  for  lantern  exhibitors  generally.  The  want  of 
some  apparatus  by  which  a supply  of  oxygen  could  be  maintained 

4—2 


46 


THE  MAGIC  LANTERN  MANUAL. 


in  connection  with  a portable  gas-holder  was  in  1868  supplied 
by  Mr.  M.  Noton,  who  was  the  first  to  describe  the  generating  of 
oxygen  gas  at  the  time  of  consumption,  by  means  of  small  retorts 
charged  with  plugs  of  chlorate  of  potash  and  oxide  of  manganese, 
which  were  alternately  subjected  to  the  flame  of  a Bunsen  burner, 
thus  generating  the  gas  as  occasion  required,  which  was  stored  in 
the  small  portable  gas-holder  forming  a part  of  the  apparatus,  and 
used  therefrom  (see  Fig.  23).  The  plugs  used  were  moulded  while 
the  mixture  was  in  a damp  state,  and,  after  being  dried,  were  ready 
for  use. 

A difficulty  was  experienced  in  extracting  the  spent  plugs  for 
re-charging,  which  necessitated  the  use  of  four,  six,  or  more  retorts, 
depending  upon  the  quantity  of  gas  required. 

To  obviate  this  difficulty,  and  to  dispense  with  a number  of 
retorts,  the  author  designed  a retort  in  which  flat  cakes  could  be 
used  instead  of  plugs  or  cylinders.  It  was  also  arranged  with  due 
consideration  to  perfect  safety,  and  the  entire  removal  of  fear  from 
the  minds  of  inexperienced  experimentalists. 

The  principle  of  the  retort  or  generator  will  be  clearly  seen 
from  the  accompanying  woodcut  (Fig.  24).  It  consists  of  two 
pieces,  a flat  plate,  and  a bell-shaped  cap,  supported  by  a stand 
in  which  is  placed  a Bunsen  burner  of  improved  construction. 
The  cap  has  an  aperture  at  the  top,  in  which  is  screwed  a pipe, 
etc.,  for  conveying  away  the  oxygen  as  made.  In  other  respects 
the  retort  proper  consists  of  two  simple  iron  castings  turned  and 
ground  to  a gas-tight  fit.  The  fastening  consists  of  a bow,  clearly 
shown  in  the  woodcut,  at  the  extremities  of  which  are  small  spiral 
springs,  so  adjusted  as  to  maintain  a pressure  equal  to  i|  lbs.  per 
square  inch,  which  pressure  is  far  in  excess  of  what  is  ordinarily 
required  for  lime  light  purposes.  Now,  it  is  obvious,  should  the 
passage  from  the  retort  be  closed  (although  in  this  apparatus  there 


THE  LIME  LIGHT 


47 


is  no  likelihood  of  such  an  occurrence),  the  pressure  in  the  retort 
would  rise  until  it  had  arrived  at  a pressure  of  i|  lbs.  per  square 
inch,  when  the  gas  would  escape  through  the  joint;  and,  as  soon 
as  the  passage  was  clear  again,  the  gas  would  take  its  right  course, 
relieving  the  pressure  inside  the  retort,  and  by  virtue  of  the  spring 
the  joint  would  close,  and  the  top  assume  its  original  position. 
When  exhibiting  this  apparatus  at  several  scientific  societies,  to 
illustrate  its  safety  qualities,  as  the  gas  was  coming  off  rapidly  the 
outlet  pipe  was  closed  (by  means  of  a tap  purposely  introduced), 


Tig.  25.  Fig  26. 


and  the  oxygen,  still  being  generated,  escaped  through  the  joint 
(as  intended)  with  perfect  safety.  To  open  the  retort  for  re-charging, 
etc.,  pull  over  the  wood  handle  fixed  to  the  top  of  the  bow,  and 
the  cap  may  be  then  removed  by  the  wood  handle  fixed  thereto, 
and,  to  close  the  apparatus,  reverse  these  operations.  The  handles 
being  made  of  wood  prevent  the  fingers  from  being  burned  when 
in  use. 

The  method  of  making  the  cakes  is  as  follows : To  four  parts 
chlorate  of  potash  and  one  part  manganese,  add  sufficient  water 
to  moisten,  not  to  wet ; after  mixing  well,  fill  the  mould,  using 
little  pressure,  smooth  off  the  surplus  with  a dinner  knife  or  a 


48 


THE  MAGIC  LANTERN  MANUAL . 


spatula,  turn  over,  and  the  cakes  will  leave  the  mould  entire. 
After  sufficient  cakes  are  thus  made,  they  are  set  to  dry,  either  by 
gentle  heat  or  spontaneously ; when  dry,  the  bottoms  are  coated 
by  dipping  into  a mixture  of  manganese  and  water  about  the  con- 
sistency of  cream ; when  dry,  they  are  ready  for  use.  This  coat- 
ing of  the  bottom  of  the  cakes  with  plain  manganese  is  to  prevent 
the  spent  cake  sticking  to  the  retort,  being  the  only  part  in  con- 
tact with  it.  These  cakes  leave  the  retort  in  their  entirety,  only 


somewhat  distended ; they  are  easy  to  produce,  clean  to  handle, 
and  as  hard  as  a piece  of  coal. 

In  addition  to  the  retort  shown  at  Fig.  24,  other  forms  were 
devised  by  the  writer. 

The  one,  Fig.  25,  for  dead  weight.  Another,  Fig.  26,  for  lever 
and  weight. 

The  writer  has  also  designed  a retort  for  the  use  of  plugs  or 
cylinders,  to  which  was  applied  the  safety-valve  in  the  dead-weight 
form.  The  principle  will  be  fully  understood  by  reference  to  the 
drawings;  Fig.  27  showing  the  retort  open;  Fig.  28  showing  it 
closed.  If  the  pressure  in  the  retort  should  from  any  cause  rise 
in  excess  of  that  to  which  it  is  weighted,  the  gas  would  be  liberated 
at  the  front  end  by  virtue  of  the  weight  which  is  hinged  to  the 


THE  LIME  LIGHT. 


49 


retort,  and  has  attached  to  it  the  cap-lid  in  such  a manner  as  not 
to  be  quite  rigid,  but  is  free  to  move  a little  so  as  to  find  its  pro- 
per position.  On  the  cap-lid  is  a small  projection  shown  in  Fig. 
28,  for  the  purpose  of  removing  any  substance  which  might  inter- 
fere with  the  joint,  and  also  permits  of  the  lid  being  ground  into 
its  proper  bed.  The  method  of  opening  and  closing  the  retort  is 


simple  : — Turn  up  the  weight  and  the  retort  is  open,  or  turn  down 
the  weight  and  it  is  closed.  Plugs  of  chlorate  of  potash  and  man- 
ganese may  be  made  and  used  in  thin  sheet-iron  cases,  if  pre- 
ferred; or  another  method  adopted  is  to  make  the  plugs  on  a 
wire,  with  a sheet-iron  disc  at  the  bottom  end,  and  a small  loop  at 
the  other  (just  resembling  a sugar-crusher). 


50  the  magic  lantern  manual . 

As  soon  as  the  plugs  are  dry  (which  they  become  much  sooner 
than  when  bottled  up  in  a tin  case),  dip  them  in  plain  manganese 
and  water;  this,  when  dry,  prevents  any  adhering  to  the  retort. 
Should  the  plug  break,  or  any  part  become  detached,  the  disc  at 
the  plug  end  attached  to  the  wire,  on  being  extracted,  brings  all 
with  it. 

At  Fig.  29  the  whole  apparatus  is  shown  packed  for  travelling, 
with  lanterns,  &c.,  in  a dry  compartment.  Fig.  30  shows  the 

apparatus  as  at  work.  Fig.  31  shows 
the  under  side  of  the  apparatus; 
and  the  lid,  with  lock-up  arrange- 
ment, partly  open,  displays  the  por- 
tion used  for  packing,  formed  by 
the  displacement-chamber,  around 
which  the  water  luting  for  the  bell 
is  poured  when  in  action.  Fig.  32 
illustrates  the  apparatus  used  as  a 
stand  for  the.  lantern. 

When  in  use  the  pressure  is  applied 
by  placing  water  in  a reservoir  pro- 
vided for  that  purpose,  thereby  main- 
taining one  uniform  pressure  through- 
out, which  can  be  regulated  accord- 
ing to  the  quantity  of  water  used.  If 
more  convenient,  any  other  substance 
than  water  may  be  adopted  for 
weighting. 

Thus  by  using  this  apparatus,  port- 
ability is  obtained,  gas-bags,  pressure 
boards,  and  weights  are  dispensed  with,  and  a continuous  supply 
of  oxygen  of  even  pressure  with  perfect  safety  is  maintained. 


Fig • 32. 


THE  LIME  LIGHT, 


51 


CONDENSED  GASES. 

In  America,  where  oxygen  is  manufactured  commercially,  cylin- 
ders of  sheet  iron  (Fig.  33)  were  introduced,  into  which  both  oxygen 
and  hydrogen  were  compressed  to  about  250  lbs.  or  300  lbs.  per 
square  inch.  This  plan  was  also  adopted  in  Brussels,  where  oxygen 
is  largely  used  for  ordinary  illuminating  purposes.  It  has  also 
been  introduced  into  this  country,  and  is  now 
sold  commercially  at  so  much  per  cubic  foot, 
and,  although  possessing  the  excellent  advantages 
of  portability  and  convenience,  in  many  ways  it 
is  nevertheless  open  to  objection  and  serious 
drawbacks,  as  the  apparatus  for  filling  the  cylin- 
ders is  too  costly  for  most  amateurs.  It  is  neces- 
sary to  send  them  to  the  manufacturer  to  be 
refilled;  this  is  in  itself  an  expense,  and  in  many 
cases  a loss  of  time.  But  the  most  serious  objec- 
tion is  that  the  cylinders  often  prove  to  be  empty 
when  they  are  expected  to  be  full,  through  some 
leaky  joint  or  connection,  unless  they  are  very 
well  made,  owing  to  the  high  pressure  used,  which 
is  ever  varying — another  serious  defect  in  the 
system.  It  will  be  clearly  seen  that,  whatever 
pressure  be  used  at  the  commencement,  after  Fig.  33. 
half  the  gas  is  consumed,  the  remaining  half  must 
have  expanded  to  double  the  volume,  and  therefore  only  half  the 
original  pressure  remains,  and  so  it  goes  on  continually  decreasing 
in  pressure,  and  requiring  constant  attention  at  the  jets  or  tap 
provided  for  the  purpose.  To  obviate  this  constant  attention, 
several  forms  of  automatic  valves  and  regulators  have  from  time 


52 


THE  MAGIC  LANTERN  MANUAL . 


to  time  been  introduced,  but  up  to  the  present  none  of  any 
practical  use  are  before  the  public  in  a reliable  form.  We  have 
heard  much  of  the  use  our  American  friends  make  of  condensed 
gas  cylinders,  and  in  reply  the  author  would  say  that  he  has  wit- 
nessed many  exhibitions  in  the  United  States,  conducted  by  the 
best  lanternists  of  America,  and,  in  every  case  where  cylinders 
were  used,  only  a single  lantern  was  in  operation,  and  generally 
their  lantern  manipulation  was  not  first-class,  or,  at  all  events,  not 
such  as  would  satisfy  many  English  lanternists  we  could  name. 

THE  ETHOXO  LIME  LIGHT. 

Before  leaving  the  sources  of  illumination,  the  “Ethoxo” 
Lime  Light  must  not  be  omitted.  Undoubtedly  the  credit  for 
the  introduction  of  this  light  is  due  to  Mr.  William  Broughton, 
and  may  be  described  briefly  by  stating  that  ether  (G4  H50)  is 
used  in  place  of  hydrogen.  Various  forms  of  vapourizers  have 
been  introduced,  but  that  by  Mr.  Broughton  is,  in  the  writer’s 
experience,  decidedly  the  best. 

The  illumination  is  quite  equal  to  most  forms  of  oxy-hydrogen 
when  blow-through  jets  are  used,  providing  a good  pressure  be 
sustained.  But  there  is  a certain  danger  attending  it  that  pre- 
cludes the  writer  from  recommending  it  (in  its  present  form,  at  all 
events),  except  by  those  who  thoroughly  understand  the  nature  of 
the  substances  in  use.  The  author  feels  that  in  writing  a book  of 
this  class,  which  may  fall  into  the  hands  of  many  whose  experience 
in  such  matters  is  very  limited,  that  it  becomes  his  duty  to  caution 
such  persons  from  using  something  that  might  endanger  life.  At 
the  same  time,  it  would  be  manifestly  unjust  to  Mr.  Broughton 
not  to  refer  to  this  light. 

After  reviewing  the  various  sources  of  illumination,  the  modes 
of  preparation  and  storing  the  gases,  the  author  is  brought  to  the 


LIME  LIGHT  JETS. 


53 


conclusion  that  for  really  first-class  exhibitions,  where  the  very 
best  results  are  desired,  and  which  have  to  be  conducted  in  various 
parts  of  the  town  or  country,  there  is  no  better  arrangement  up  to 
the  present  time,  everything  considered,  than  a pair  of  gas-bags, 
and  double-pressure  frame,  using  mixed  jets. 

JETS. 

By  far  the  most  powerful  and  economical  form  of  jet  is  the 
Oxy-hydrogen  (Fig.  34)  often  called  the  Mixed  Jet.  As  will  be 
seen  in  the  illustration,  each  gas  is  carried  in  a separate  tube  to  a 
chamber  under  the  nozzle,  in  which  chamber  the  gases  are  mixed 


just  before  ignition.  For  the  successful  working  of  this  jet  it  is 
imperative  that  both  the  oxygen  and  hydrogen  be  under  equal 
pressure  (see  description  of  Double  Pressure  Frame,  p.  40). 

Originally  the  oxygen  and  hydrogen  were  mixed  in  the  bag,  in 
the  proportion  of  one  part  by  volume  of  oxygen  to  two  of  hydrogen, 
and  only  one  tube  was  necessary ; but  this  was  a most  dangerous 
proceeding,  for  should  the  pressure  be  relieved  by  any  chance 
from  the  bag  containing  the  mixed  gases  at  the  time  the  light  was 
burning  at  the  nozzle  of  the  jet,  the  combustion  would  be  instantly 
carried  down  the  supply-tube  and  a fearful  explosion  would  ensue. 
It  was  found  safer  therefore,  to  use  the  gases  in  separate  bags,  and 
to  mix  them  in  the  chamber  for  that  purpose  just  previous  to 
ignition  at  the  nozzle  of  the  jet;  but  even  in  this  case,  if  the  bags 


54 


THE  MAGIC  LANTERN  MANUAL. 


be  not  equally  weighted  (a  case  which  might  easily  occur  through 
unequal  sizes  of  bags  or  pressure  boards,  or  by  substituting  manual 
pressure  for  weights),  the  gas  under  the  heaviest  pressure  would 
be  forced  into  the  other  bag,  and,  as  in  the  former  case,  the  re- 
lieving of  the  pressure  would  terminate  the  proceedings  with 
equally  dangerous  results. 

An  accident  of  this  class  occurred  in  the  presence  of  the  writer, 
through  a gentleman  inadvertently  putting  his  foot  on  to  the  bag 
to  give  a little  more  pressure  : as  soon  as  he  withdrew  it  a fearful 
crash  was  heard ; fortunately  no  one  was  injured,  but  the  sudden 
concussion  of  the  air  produced  a temporary  deafness,  besides 
more  or  less  destruction  to  all  the  apparatus  around. 

So  let  it  be  borne  in  mind  that  when  using  mixed  gases,  never 
to  relieve  the  pressure  or  adjust  the  bags  or  weights  in  any  case 
when  the  light  is  burning.  The  best  effect  from  a mixed  jet  is 
obtained  at  high  pressures.  The  author  has  used  this  form  of  jet 
at  a pressure  equal  to  a column  of  water  120  inches  in  height : in 
this  instance  it  is  necessary  to  use  hard  limes,  and  a clockwork 
arrangement  to  automatically  rotate  the  limes,  and  gradually  give 
them  an  upward  spiral  motion. 

“ The  safety  ” oxy-hydrogen,  or  “ blow-through  ” jet,  although 
inferior  in  illuminating  power  to  the  above,  is  usually  sufficient  for 
pictures  of  12  to  14  feet  diameter;  but  it  must  be  mentioned  that 
more  gas  is  consumed  to  produce  the  same  result  than  is  required 
with  the  mixed  gases.  With  this  jet  it  is  only  necessary  that  the 
oxygen  be  under  pressure,  the  hydrogen  may  be  used  direct  from 
the  main ; this  is  a great  convenience  in  many  instances.  It  will 
be  seen  in  Fig.  35  that  in  this  jet  the  gases  are  mixed  at  the  nozzle, 
and  therefore  all  fear  of  a catastrophe  through  the  gases  becom- 
ing mixed,  even  under  unequal  pressure,  is  abolished. 

The  hydrogen  is  conducted  up  the  left-hand  tube,  the  extremity 


LIME  LIGHT  JETS . 


55 


or  nozzle  of  which  is  of  wide  bore,  the  oxygen  being  conveyed  in 
the  right-hand  tube,  and  from  a fine  nozzle  is  blown  through  the 
hydrogen.  Softer  limes  may  be  used  with  this  jet  to  advantage. 

The  effect  of  the  gas  upon  the  lime  is  to  puncture  it,  causing 
small  cavities ; and  when  a cavity  has  been  formed,  the  light  is  by 
no  means  so  effective,  and  there  is  a great  liability  of  the  flame 
being  thrown  forward,  thereby  endangering  the  condenser  by 
fracture.  It  is  necessary,  therefore,  to  slightly  rotate  the  lime 
after  showing  each  picture,  and  this  is  most  conveniently  done 
after  dissolving,  and  when  the  light  is  turned  low. 


Several  means  for  rotating  the  limes  have  been  devised  to  work 
from  the  rear  of  the  lantern.  An  exceedingly  ingenious  arrange- 
ment  was  some  time  ago  introduced,  which  will  be  seen  at  Fig. 
36,  consisting  of  a spiral  spring  connecting  the  vertical  lime  pin, 
with  the  long  horizontal  rod,  on  the  end  of  which  is  a milled 
head,  a little  beyond  the  taps  of  the  jets. 

This  jet  forms  a blow-through,  and  a high  pressure  or  mixed 
jet,  by  simply  unscrewing  a collar  and  substituting  one  nozzle  for 
another. 

In  the  jet,  illustrated  at  Fig.  37,  brass  cog-wheels  are  used  in 
connection  with  a screwed  lime  pin  to  range  and  turn  the  lime, 
and  although  slightly  more  expensive  than  the  foregoing  jet,  is  a 
a far  better  arrangement.  Mr.  Place,  optician,  has  introduced 


0 


THE  MAGIC  LANTERN  MANUAL. 


a very  excellent  form  of  jet,  the  lime  pin  being  provided  with 
a very  quick  pitch  thread  or  screw,  so  that  one  turn  of  the 
pin  raises  the  lime  about  an  eighth  of  an  inch,  and  so  prevents 


Fig.  37- 


the  flame  projecting  into  the  hole  worn  out  in  the  lime,  upon  the 
completion  of  a revolution,  as  is  the  case  with  the  very  fine  thread 
lime  pins. 

OXY-CALCIUM  OR  SPIRIT  JET. 

This  jet  is  only  used  when  hydrogen  is  not  obtainable  or  incon- 
venient to  get  at.  Many  modifications  of  this  style  have  been 

devised  with  more  or  less 
success.  That  illustrated  at 
Fig.  38  is  a good  form. 

It  is  very  essential  that  the 
reservoir  for  the  spirit  of  wine 
be  kept  cool,  also  accessible 
for  recharging  with  spirit,  and  that  the  wick-holder  be  made  to 
hold  a large  wick  capable  of  giving  a good  compact  flame. 

No  possible  chance  of  explosion  could  occur  with  this  form  of 
jet,  though  the  writer  has  known  of  clumsy  operators  setting  fire  to 
the  spirits. 

Soft  limes  should  be  used  with  it,  and  large  nozzles,  with  not 


Fig.  38. 


LIME  LIGHT  JETS.  57 

too  excessive  a pressure,  have  been  found  to  produce  the  best 
results. 

The  taps  of  oxy-hydrogen  jets  should  be  lacquered  of  different 
colours,  so  as  to  be  distinguishable  in  the  dark. 


Tig  39* 


It  is  important  that  no  solder  be  used  in  the  construction  of  the 
jets,  and  that  the  nozzles  are  removable  or  accessible  for  cleaning. 
In  jets  of  the  best  quality  the  nozzles  are  made  of  platinum.  The 
lime-pins  should  be  large  enough  to  hold  two  limes  one  above  the 
other,  so  that  in  case  of  accident  to  one  lime  another  is  close  at 


58 


THE  MAGIC  LANTERN  MANUAL. 


hand,  warm  and  ready  for  use.  A small  pair  of  tongs  are  useful 
in  removing  broken  limes. 

A most  ingenious  burner  has  been  devised  for  use  with  the 
Sciopticon,  by  Mr.  L.  Marcy,  the  inventor  of  that  instrument.  It 
takes  the  exact  position  of  the  oil  lamp.  This  burner  is  provided 
with  three  separate  nozzles,  and  can  be  used  as  a mixed  gas-jet,  a 
blow-through  jet,  or  for  oxy-calcium  lime  light.  It  is  shown  at 
Fig.  39.  The  body  b is  formed  of  a block  of  hard  wood,  upon 
which  the  various  parts  are  mounted.  At  o and  h are  the  taps  for 


Fig.  40. 


the  admission  of  oxygen  and  hydrogen,  and  which  are  made  dis- 
similar, so  that  each  may  be  readily  distinguished  in  the  dark. 
Between  these  taps  is  a screw  with  a milled  head  at  s for  raising  or 
lowering  the  jet  to  the  required  position.  The  lime  l,  which  is  of  disc 
form,  is  so  placed  that  the  flame  impinges  upon  its  circumference, 
and  therefore  a great  amount  of  surface  is  available.  The  lime-holder 
is  placed  through  the  chimney  aperture,  and  is  held  in  position  by 
the  piece  attached  at  right  angles,  as  shown  in  the  illustration. 


LIME  LIGHT  JETS. 


59 


The  lime  is  easily  turned  in  its  cradle.  At  d and  e are  two  boxes 
in  which  the  two  jets  not  in  use  are  kept,  and  f is  a brass  door 
for  closing  same.  At  v is  a small  piece  of  steel,  mounted  with 
brass  milled  head,  which  can  be  used  to  clean  the  jets  when  re- 
quired. The  whole  is  very  accessible  for  cleaning,  and  capable  of 
every  adjustment.  It  is  shown  in  position  at  Fig.  40. 


The  three  different  jets  are  illustrated  at  Figs.  41,  42,  43. 


Fig.  41.  Fig.  42.  Fig.  43. 


Fig.  41  represents  the  one  used  for  the  alcohol  flame  or  oxy- 
calcium  jet ; the  wick  w being  fed  through  the  hydrogen-tap  from 
a reservoir  of  alcohol,  with  which  each  burner  is  supplied. 

Fig.  42  represents  the  blow-through  jet,  and  Fig.  43  the  oxy- 
hydrogen  or  mixed  jet,  each  gas  being  conveyed  through  its 
respective  tube  o or  h,  and  is  mixed  in  the  small  chamber  at 
c previous  to  emerging  through  the  nozzle  m. 


6o 


THE  MAGIC  LANTERN  MANUAL. 


As  before  stated,  it  is  only  by  the  use  of  mixed  gases  that  an 
explosion  can  occur,  for  both  oxygen  and  hydrogen  are  perfectly 
harmless  if  kept  to  themselves,  as  hydrogen  will  not  burn  unless 
oxygen  be  present,  and  though  oxygen  is  the  supporter  of  com- 
bustion, it  will  not  burn  alone ; therefore  it  is  clear  that  so  long  as 
these  gases  are  kept  separate  no  danger  can  accrue. 

To  provide  against  the  possibility  of  accident  when  using  mixed 


Fig.  44. 

gases,  various  devices  have  been  proposed,  some  very  ingenious, 
and  some  very  inefficient,  with  the  object  of  preventing  the  flame 
being  drawn  down  the  supply-pipes.  Layers  of  fine  wire  gauze 
have  been  introduced  into  the  supply-tubes.  This  plan  was  found 
inefficient,  as  an  oxy-hydrogen  flame  could  easily  be  made  to  pass 
through  the  gauze. 

Mr.  J.  T.  Taylor  devised  three  different  forms  of  safety  valves, 
shown  respectively  at  Fig.  44.  It  will  be  seen  that  the  two  out- 
side ones  are  only  intended  to  be  used  in  the  positions  shown  in 
the  woodcut.  The  centre  one  is  by  far  the  best  arrangement,  and 
possesses  the  advantage  of  being  used  in  any  position,  therefore  it 
is  the  most  approved  form.  It  consists  of  a metal  valve,  and  a 
fine  spiral  spring,  so  adjusted  that  very  little  force  is  required  to 
open  it,  and  remaining  closed  in  its  normal  position  prevents  any 
return  of  gas. 

Gurney’s  arrangement  was  to  pass  the  gas  through  a slight 


BACK  PRESSURE  VALVES. 


6 1 


column  of  water  under  the  jet ; but  this  was  not  a convenient  ar- 
rangement, and  in  many  cases  was  not  effective. 

Mr.  S.  Highley  improved  upon  this  latter  plan  by  an  additional 
valve,  and  with  his  arrangement  an  explosion  would  be  impossible. 
But  even  this  plan  was  not 
without  fault,  being  somewhat 
complicated,  and  the  writer 
has  often  known  lan- 
ternists  to  shirk  the  use  of 
many  good  things  on  account 
of  the  extra  trouble  in  their 
adoption.  He  has  therefore 
devised  a valve  styled  a “ back- 
pressure valve,”  clearly  illus- 
trated at  Fig.  45.  It  consists 
of  two  parts  made  in  brass,  be- 
tween which  is  placed  a thin 
india-rubber  or  oiled  silk  dia- 
phragm, through  which  four 
or  five  holes  are  made,  as  shown 
at  b.  The  area  of  these  orifices 
is  in  excess  of  the  ingress-tube, 
therefore  the  slightest  pressure 
entering  the  valve  in  the  direc-  Fig.  45. 

tion  of  the  arrow  would  act 

upon  the  diaphragm  so  as  to  open  the  valve,  and  allow  the  gas  to 
pass  with  the  least  possible  resistance  on  account  of  the  large  area 
of  diaphragm  exposed  to  pressure. 

As  the  valve  in  its  normal  condition  is  closed,  nothing  whatever 
could  pass  the  opposite  way,  and  the  greater  the  pressure  in 
this  direction  the  tighter  would  the  valve  be  closed.  Both 

5 2 


62 


THE  MAGIC  LANTERN  MANUAL. 


india-rubber  and  oiled  silk  withstand  the  action  of  the  gases  mode- 
rately well;  but  should  occasion  ever  require,  the  valve  could  be 
readily  taken  to  pieces,  and  a new  diaphragm  be  inserted  in  a few 
minutes.  This  valve  has  been  subjected  to  most  severe  tests,  and 
in  no  one  instance  has  it  failed  to  act  efficiently.  A moment’s 
reflection  will  show  that  no  such  appliances  are  at  all  necessary 
when  using  blow-through  jets,  but,  in  the  case  of  mixed  jets,  a 
back-pressure  valve  should  be  used  on  each  supply  pipe,  placed 
as  near  the  lantern  as  possible. 

A short  time  ago  Mr.  Broughton  introduced  a flame  interceptor, 
consisting  of  a small  chamber,  which  was  filled  with  powdered 
pumice  and  fixed  under  the  nozzle  of  the  jet.  This  has  been 
considered  very  effectual  in  performing  its  functions. 


PHOTOMETRY. 

IN  estimating  or  measuring  light,  instruments  are  necessary, 
called  Photometers,  the  standard  of  comparison  being  a 
candle,  defined  by  Act  of  Parliament  as  a sperm  candle  of  six  to 
the  pound,  and  burning  at  the  rate  of  120  grains  per  hour,  and, 
although  such  candles  are  offered  for  sale,  it  seems  unfortunate 
that  no  better  standard  was  fixed  upon,  as  candles,  commercially, 
are  not  manufactured  alike  in  different  places,  and  the  varying 
quality  of  the  material,  together  with  the  thickness  of  the  wicks, 
make  serious  differences  in  the  results  of  experiments  in  con- 
sequence. 

We  hope,  ere  long,  to  see  a better  and  universal  standard 
accepted  by  all  nations,  as  several  have  already  been  brought  to 
notice,  and  others  are  still  being  submitted. 

Of  the  various  forms  of  “ Photometers,”  the  simplest  are,  perhaps, 


PHOTOMETRY . 


63 


the  “ Rumford  ” or  the  " Bunsen.”  At  Fig.  46  is  an  illustration 
of  the  former}  the  principle  being  based  upon  the  comparison  of 
shadows.  The  light  to  be  tested  should  be  placed  at  some  given 
distance  from  the  screen,  which  may  be  transparent  and  viewed 
from  behind,  or  opaque  and  viewed  in  front.  A rod  is  then  fixed 
a few  inches  from  the  screen,  on  which  a shadow  will  be  thrown. 


Fig.  46. 


Now  place  the  candle  at  such  a distance  that  another  shadow  of 
equal  depth  is  seen  alongside  the  first  one.  The  distance  of  each 
should  be  measured  off,  each  measurement  should  be  squared, 
and  on  dividing  the  greater  by  the  lesser,  the  quotient  will  be  the 
illuminating  candle  power. 

“ Bunsen’s  Photometer”  consists  of  a white  paper  screen,  with 
a grease-spot  in  the  centre.  The  light  to  be  tested  is  placed  at  a 
given  distance  on  one  side  of  the  screen,  and  the  candle  at  the 


64 


THE  MAGIC  LANTERN  MANUAL. 


other,  the  distance  being  regulated  so  that  the  grease-spot  appears 
neither  lighter  nor  darker  than  the  rest  of  the  screen — in  fact,  is 
invisible  from  either  side.  The  respective  distances  are  now 
measured  off,  and  their  squares  are  proportional  to  the  illuminat- 
ing powers.  In  comparing  lights  no  optical  arrangements  should 
be  used,  as  this  would  seriously  interfere  with  the  results.  Thus, 
in  testing  the  lime  light,  the  jet  should  be  entirely  removed  from 
the  lantern,  and  tested  without  being  shown  through  either  con- 
denser or  objective. 

A series  of  experiments  were  gone  into  by  the  author,  in  which 
both  “Rumford’s ” and  “ Bunsen’s”  Photometers  were  used,  both 
kinds  being  adopted,  so  as  to  check  the  results.  Below  will  be 
found  the  averages  of  several  illuminating  powers,  as  resulting 
from  those  experiments  : — 

Sciopticon  . . . . 41.7  standard  candles. 

Oxy-calcium 152  „ „ 

Safety  or  blow-through  jet  .208  .,  „ 

Oxy-hydrogen  or  mixed  gases  430  ,,  „ 


DISSOLVING  VIEWS. 

ISSOLVING  VIEWS  were  originally  invented  by  Mr. 


Henry  Langdon  Childe,  who  in  1811  publicly  exhibited 
them  for  the  first  time.  The  effect  was  produced,  as  now,  by  the 
employment  of  two  lanterns,  with  an  apparatus  arranged  in  front 
of  the  objective  lenses,  whereby  the  light  from  one  lantern  is 
admitted  on  the  screen  at  the  same  time  that  the  light  from  the 
other  is  obliterated.  This  apparatus  is  styled  the  “ Dissolver,” 
and  at  Fig.  47  will  be  seen  a pair  of  lanterns  with  the  same 
applied.  It  consists  of  a serrated  plate  or  comb,  placed  in  front 


DISSOLVING  VIE WS. 


65 


of  the  objectives,  and  attached  to  a vertical  bar  with  a rackwork 
and  pinion ; a handle  at  the  back  of  the  lanterns,  so  placed  as  to 
be  accessible  to  the  operator,  gives  motion  to  the  rack  and  pinion, 
which  moves  the  comb  vertically,  thereby  alternately  shutting  out 


Dig.  47. 


the  light  from  each  lantern.  In  the  illustration  the  right-hand 
lantern  is  closed,  while  the  left-hand  one  is  full  open,  and  a 
picture  in  this  lantern  is  supposed  to  be  projected  on  the  screen. 
Now,  by  turning  the  handle,  the  “ Dissolver  ” will  rise,  and  in  so 
doing  will  gradually  open  the  right-hand  lantern  objective;  at  the 
same  time  it  will  as  gradually  cover  that  of  the  left-hand  lantern : 


66 


THE  MAGIC  LANTERN  MANUAL, 


thus  one  picture  is  caused  to  fade  away  at  the  same  time  that 
another  one  is  made  to  appear. 

The  blending  into  each  other  of  the  pictures  (with  no  increase 
or  decrease  of  illumination)  is  such  that  the  transformation,  when 
suitable  pictures  are  selected,  is  most  wonderfully  beautiful  and 
fairylike. 

Prior  to  the  introduction  of  Mr.  Childe’s  Dissolving  Views,  the 
lantern  was  considered  merely  as  a toy,  and  not  of  educational  value. 

Probably  the  earliest  employment  of  the  Magic  Lantern  to 
educational  purposes  was  originated  by  the  late  Mr.  Richard 
Vaughan  Yates,  of  Liverpool.  Mr.  Yates,  having  made  a tour  in 
the  Holy  Land,  on  his  return  had  a number  of  paintings  on 
glass,  executed  by  some  of  the  best  artists  of  the  day,  to  illustrate 
the  principal  places  of  interest  visited  during  his  travels. 

Mr.  Yates,  assisted  by  Mr.  Dancer,  optician,  at  that  time  of 
Liverpool,  exhibited  these  views  to  delighted  audiences.  The 
late  Mr.  John  Smith,  one  of  the  proprietors  of  the  Liverpool 
Mercury , was  so  impressed  by  these  exhibitions,  as  showing  the 
lantern’s  importance  as  an  educational  instrument,  that  he  arranged 
an  extended  course  of  lectures  on  geography,  to  be  illustrated  by 
aid  of  the  lantern.  These  lectures  were  delivered  and  illustrated  by 
the  above  means  in  all  the  principal  towns  of  the  kingdom,  and 
proved  very  remunerative. 

The  illumination  of  lantern  exhibitions  up  to  this  period  had 
been  effected  by  means  of  oil  lamps,  which  did  not  prove  satis- 
factory in  some  of  the  larger  rooms,  and  in  1837,  Mr.  Dancer, 
optician,  then  of  Manchester,  suggested  to  Mr.  Smith  the  use  of 
the  “ lime  light,”  or,  as  it  was  then  styled,  the  “ Drummond  light,” 
which  at  that  time  was  in  use  for  gas  microscopes  only. 

The  artists  who  painted  the  slides  predicted  that  their  pictures 
would  be  ruined  by  such  a light. 


DISSOLVING  VIEWS . 


6? 


The  new  illuminating  power  supplied  Mr.  Smith’s  wants  admi- 
rably, and  the  success  of  these  lectures  at  once  induced  Mr.  James 
Robinson,  of  Liverpool,  to  commence  in  a similar  line,  and  Mr. 
Dancer  supplied  him  with  an  elaborate  oxy-hydrogen  lantern, 
having  9-inch  condensers.  The  directors  of  the  Manchester  Me- 
chanics5 Institution  have  largely  contributed  to  popularize  the  Magic 
Lantern  as  an  educational  instrument,  and  their  annual  exhibition 
proved  very  remunerative  and  attractive.  To  Mr.  Dancer  is  due 
the  credit  also  of  having  first  exhibited  photographs  in  the  lantern, 
the  first  one  being  of  the  programme  at  the  above  institution.  At 
this  time  Messrs.  Negretti  & Zambra  were  the  sole  agents  for  the 
magnificent  stereoscopic  slides  of  M.  Ferrier,  of  Paris,  and  a 
number  of  these  slides  were  sent  down  by  them  to  Manchester.  Mr. 
Dancer  prepared  them  for  the  lantern  by  dissolving  away  the  white 
wax  with  which  they  were  backed,  and  under,  the  excellent  manage- 
ment of  Mr.  E.  Hutchins,  the  Secretary  of  the  above  institution^ 
these  exhibitions  justly  obtained  a wide  celebrity,  and  many  other 
public  institutions  throughout  the  kingdom  were  prompted  to  enter 
into  a similar  enterprise  with  more  or  less  success. 

Now  that  the  introduction  of  photography  in  connection  with 
the  Magic  Lantern  had  become  instituted,  its  value  as  an  educa- 
tional instrument  became  more  apparent,  for  although  many  of 
the  hand-painted  slides  were  very  beautiful  and  artistically  pro- 
duced, a single  picture  costing  in  some  instances  as  much  as  twenty 
guineas,  yet  the  artist,  however  eminent,  can  never  aspire  to  the 
accuracy  of  photography  in  minute  detail. 

A climax  would  now  seem  to  have  been  reached  when  Mr. 
Dancer  conceived  the  idea  of  dissolving  by  shutting  off  the  gas 
from  one  lantern  and,  at  the  same  time,  turning  it  on  to  the  other 
lantern.  For  this  purpose  he  had  taps  arranged  to  shut  off  the 
gases  from  each  lantern  alternately,  thereby  dispensing  with  the 


68 


THE  MAGIC  LANTERN  MANUAL 


mechanical  dissolver  already  described.  The  first  of  these  was 
made  by  Mr.  Dancer  for  the  Manchester  Mechanics’  Institution, 
which,  on  being  tried,  surpassed  in  result  all  expectation,  for  not 
only  was  the  dissolving  better,  but  about  50  per  cent,  of  the  gas 
was  saved. 

Mr.  Noton  afterwards  devised  a Single  Plug  Dissolver,  and  pub- 
lished a description  of  it  in  the  British  Journal  of  Photography , 
March  15  th,  1864. 


It  has  proved  equally  applicable  with  the  mixed  jet,  the  safety 
blow-through,  and  the  oxy-calcium  lime  light,  and  has,  since  its 
introduction,  been  modified  in  various  ways,  with  pretty  much  the 
same  result. 

The  Universal  Gas  Dissolver,  shown  at  Fig.  48,  is  a modification 
of  the  Single  Plug  Dissolver,  shewn  by  Mr.  Noton.  As  will  be 
seen,  this  tap  consists  of  a single  plug,  in  which  two  cavities  are 
cut  in  such  positions  that  the  gases  enter  at  their  respective 


DISSOLVING  VIEWS . 69 

branches  indicated  by  o and  h,  and  when  the  lever  is  upright  the 
passage  is  clear  to  both  lanterns. 

o1  and  h1  must  be  connected  to  the  jet  of  one  lantern,  and 
o2  and  h2  to  the  other.  When  the  lever  is  drawn  to  the  right 
hand,  the  gas  is  shut  off  from  the  top  jet,  and  when  to  the  left  the 
bottom  jet,  enough  gas  escaping  along  the  bye-passes,  when  the 
stop-cock  is  slightly  open  to  keep  the  jet  alight  without  shewing  an 
image  on  the  screen. 

These  small  stop-cocks  can  be  adjusted  at  the  commencement 
of  an  exhibition  to  the  size  of  light  required.  It  is  in  many  cases 
advantageous  to  have  both  lanterns  fully  illuminated  at  the  same 
time  for  the  production  of  effects,  such  as  lightning,  the  bursting 
of  shells,  etc.  This  tap  altogether  is  exceedingly  well  finished, 
and  very  accessible  for  cleaning. 

Another  very  effective  and  simple  dissolving  tap  is  styled  the 
“ Polytechnic  Gas-Dissolver,”  an  illustration  of  which  is  at  Fig.  49, 


Fig.  49. 

and  consists  of  a single  plug,  arranged  to  cut  off  the  gas  from  each 
lantern  alternately;  which,  beside  possessing  the  advantage  of 
being  able  to  have  both  lanterns  fully  illuminated  at  one  time,  by 
simply  turning  the  lever  to  the  back,  both  gases  are  shut  off,  as  is 


?o 


THE  MAGIC  LANTERN  MANUAL. 


sometimes  required  when  a break  or  interval  occurs  in  the  enter- 
tainment for  the  introduction  of,  say,  a little  music.  Thus  the 
trouble  of  turning  off  the  gas  at  the  bags  is  avoided,  and  at  re- 
starting no  adjustments  are  necessary.  Provision  is  made  in  the 
plug  so  that  the  hydrogen  may  pass,  so  as  to  retain  a faint  light 
alternately  in  each  lantern  as  the  gases  are  shut  off.  In  making 
the  connections  with  this  dissolver,  the  gases  are  to  be  introduced 
at  the  branches  indicated,  o and  h,  and  the  branches  marked 
o1  and  h1  must  be  connected  with  the  jets  of  one  lantern,  and 
those  marked  o2  and  h2  must  be  connected  with  the  jets  of  the 
other. 

The  dissolving  taps  already  described  apply  to  the  double  or 
Biunial  lantern,  and  for  such  are  all  that  can  be  desired ; but  for 
a triple  lantern  it  will  be  seen  that  some  further  arrangement  will 
be  necessary,  and  to  this  subject  the  writer  has  given  consider- 
able attention.  Single  plug  dissolvers  for  triple  lanterns  have 
been  made,  and  recommended  as  the  most  perfect  and  simple 
dissolver ; but  the  experience  of  the  writer  does  not  bear  this  out 
in  fact. 

There  are  triple  lanterns  arranged  with  a six-way  dissolver, 
Fig.  48,  connected  with  the  two  lower  jets,  and  a single  or  four- 
way dissolver  attached  to  the  top  jet ; but  by  far  the  most  effective 
arrangement  is  that  which  the  writer  has  successfully  adopted  for 
many  years — that  of  a single  or  four-way  dissolver  to  each  jet. 
Recently  Mr.  Steward  has  made  an  addition  to  this  system,  con- 
sisting of  vertical  rods,  attached  to  the  levers  by  clamp  tubes, 
thereby  enabling  any  two,  or  all  three,  jets  to  be  brought  into 
combination,  or  use  singly  in  an  instant.  These  dissolvers  are 
shown  in  positions  at  Fig.  55,  page  78. 

Dissolving  taps  and  jets,  however  well  made,  require  cleaning 
periodically,  and  before  use  they  should  be  taken  to  pieces  and 


THE  BIUNIAL  LANTERN. 


71 


cleaned.  The  pipes  should  be  blown  through  to  see  that  they  are 
perfectly  free  and  clean,  and  the  nozzles  of  the  jets  should  be 
cleaned  with  a piece  of  soft  copper  wire,  and  freed  from  any 
particles  of  lime  which  may  have  collected  there.  Plugs  of  the 
dissolvers  and  jets  should  be  smeared  with  a trace  of  fine  olive  oil, 
and  gas-bag  taps  are  better  lubricated  with  a little  pure  tallow. 
Burnt  india-rubber  has  been  recommended  as  a lubricant  for  the 
plugs  of  such  apparatus  as  come  in  contact  with  oxygen,  but  this 
seems  merely  to  be  an  excuse  for  a badly-fitting  plug. 


HIS  lantern,  illustrated  at  Fig.  50,  combines  two  lanterns  in 


one  body,  having  their  optical  systems  placed  one  above 
the  other,  and  is  the  most  popular  form  of  dissolving  view  appara- 
tus in  general  use. 

The  bodies  are  generally  constructed  of  mahogany,  which 
should  be  well  seasoned,  and  provided  with  a sheet-iron  lining, 
between  which  and  the  body  there  should  be  a cavity  forming  an 
air  passage.  The  cavity  should  be  open  at  the  bottom,  and  the 
sheet-iron  lining  is  generally  made  about  a quarter  of  an  inch 
higher  than  the  body,  so  that  the  dome  top  does  not  rest  on  the 
wood  body,  but  on  the  iron  lining ; thereby  the  air  passage  is  open 
at  the  top  also,  and,  forming  a free  passage  for  air,  the  lantern  is 
kept  cool.  Two  doors,  one  for  each  jet,  are  better  than  one  large 
one,  and  in  the  best  lanterns  two  doors  are  provided  at  each  side, 
with  blue  glass  windows  fitted  in  brass  cells,  through  which  the 
light  may  be  viewed  when  making  adjustments,  etc.  The  fronts 
may  be  of  wood  and  tin,  or  wholly  of  brass,  which  latter  is  the 
best,  and  generally  more  rigid.  The  tubes  are  generally  telescopic 


THE  BIUNIAL  LANTERN. 


THE  “LUKE”  BIUNI AL  LAN  TEEN. 


73 


and  provided  with  caps.  The  slide  stage  should  be  open  top, 
bottom,  and  both  sides,  and  provided  with  a roller  curtain  slide. 

The  discs  are  brought  concentric  on  the  screen  by  means  of 
milled-headed  screws  in  front,  the  lower  optical  system  being 
hinged  at  the  top,  and  the  upper  one  hinged  at  the  bottom,  as 
shown  in  the  illustration. 

The  jets  and  dissolving  taps  may  be  similar  to  those  already 
described. 

The  packing  box  may  be  of  any  convenient  form.  Usually  it 
is  too  low  in  itself  to  answer  for  a stand  upon  which  to  fix  the 
lantern  when  in  use.  The  illustration  shows  a box,  in  which  slides 
and  other  accessories  are  packed,  so  constructed  as  to  form  a 
suitable  stand,  and,  when  covered  with  drapery  of  approved 
colour,  and  the  lantern  placed  on  the  top,  the  whole  forms  a hand- 
some piece  of  apparatus. 


THE  “LUKE”  BIUNIAL  LANTERN. 


HIS  lantern  is  similar  in  construction  to  the  Biunial  pre- 


viously described,  except  that  the  adjustment  of  the 
optical  systems  for  centreing  the  discs  is  reversed,  being  hinged 
at  the  top  and  bottom,  and  the  adjusting  screws  in  the  centre  (see 
Fig.  51.)  The  body  is  constructed  of  stout  japanned  tin,  which, 
though  not  so  handsome  in  appearance,  has  the  advantage  of 
lightness,  and  for  this  reason  is  now  used  by  many  lecturers  who 
are  accustomed  to  travel  about  the  country.  The  slide-stages  are 
open  top  and  bottom,  as  well  as  both  sides,  and  provided  with  a 


74 


THE  MAGIC  LANTERN  MAN  GAL. 


roller  curtain  shutter.  The  condensers  are  4 inches  diameter  and 
the  objectives  achromatic,  of  long  and  short  focus,  with  brass 
sliding  tubes.  The  jets  and  dissolving  tap  may  be  equal  to  those 


Fig.  51. 


supplied  with  the  very  best  lantern,  and  therefore  the  effect  pro- 
duced quite  as  good.  The  packing  case,  which  forms  a stand, 
measures  18  inches  high,  17  inches  wide,  and  8|  inches  deep. 


DANCER'S  LANTERN 


7 5 


DANCER’S  LANTERN. 

THIS  lantern  was  one  of  the  most  perfect  of  its  day.  As  will 
be  seen  (Fig.  52),  one  body  combines  in  it  the  two  optical 
systems,  which  are  placed  diagonally  as  shown.  By  this  arrange- 
ment the  centres  are  brought  as  near  to  each  other  as  possible,  still 


Fig • 52* 


allowing  ample  room  for  the  manipulation  of  the  slides  either  hori- 
zontally or  vertically,  the  latter  being  convenient  for  effects,  such 
as  balloon  ascents,  etc.  The  discs  are  brought  concentric  on  the 
screen  by  an  adjusting  screw  brought  through  and  arranged  at  the 
back  of  the  lantern.  The  heat  emanating  from  the  lower  jet  in 
no  way  affects  the  upper  one ; no  tall  chimney  is  requisite,  and  a 
neat  flat  top  is  arranged  so  that  no  light  can  escape,  while  ample 
provision  is  made  for  the  exit  of  the  heated  air,  and  perfect  venti- 
lation is  secured. 


6 


76 


THE  MAGIC  LANTERN  MANUAL. 


CHADWICK’S  LANTERN, 

IN  the  early  part  of  the  year  1878  the  author  introduced  to  the 
notice  of  the  members  of  the  Manchester  Photographic 
Society  a small  pair  of  lanterns,  which  were  admired  for  their  neat- 
ness, simplicity,  and  compactness.  It  will  be  seen  in  the  illustra- 


tions (Figs.  53  and  54)  that  the  apparatus  consists  of  two  separate 
lanterns,  placed  one  over  the  other.  A hinged  piece  attached  to 
the  bottom  of  each  lantern  forms  a means  of  coupling,  and 
also  allows  of  the  adjustment  necessary  to  bring  the  discs  concentric 
on  the  screen.  When  once  adjusted,  they  are  kept  in  position  by 
two  slotted  bars  and  milled-headed  screws,  as  shown  in  the  illus- 
trations. The  hinged  piece  on  the  bottom  lantern  also  admits  of 
any  necessary  adjustment,  and  also  forms  a means  of  securing  the 
whole  to  a table,  stand,  or  tripod  top.  The  bodies  were  made  of 
mahogany,  the  inside  dimensions  being  5 inches  square,  lined  with 
sheet  tin  (allowing  an  air  space  between  the  lining  and  the  body), 


THE  TRIPLE  LANTERN. 


77 


and  so  perforated  as  to  prevent  the  emission  of  light,  while  securing 
perfect  ventilation.  The  conical  fronts  holding  the  objectives  were 
attached  to  the  bodies  by  screws,  the  holes  in  the  flanges  of  the 
fronts  being  slotted,  so  that  they  could  be  easily  detached,  and  if 
required  packed  inside  the  lanterns.  The  apertures  for  the  pictures 
were  made  of  the  standard  width,  in  which  were  placed  registering 
carriers,  a description  of  which  is  given  later.  The  jets  may  be  of 
any  approved  form,  and  the  lime  and  light  can  be  viewed  from  the 
back  by  reflection  from  the  condensers  or  through  the  blue  glass 
windows  in  the  sides.  When  necessary,  a third  lantern  (an  exact 
duplicate  of  the  other  two)  can  be  placed  on  the  top,  or  the  two 
lanterns  may  be  used  side  by  side  or  singly.  With  these  lanterns 
the  author  has  shown  large-size  discs  to  the  greatest  perfection,  and 
for  an  amateur  who  wishes  to  construct  a lantern  for  his  own  use 
nothing  can  be  much  simpler. 


HIS  elaborate  instrument  is  in  optical  and  mechanical  detail 


similar  to  the  Biunial,  at  page  72,  with  the  addition  of  a 
third  lantern  placed  on  the  top  (Fig.  55),  which  may,  however,  be 
removed  at  will,  and  used  as  a single  lantern.  Also  the  two  lower 
lanterns  may  be  used  as  a complete  biunial.  The  advantage  of 
a third  lantern  for  effects  was  no  doubt  first  suggested  by  the 
Rev.  Canon  Beechey.  Although  many  charming  effects  may  be 
shown  by  a biunial  lantern,  they  can  generally  be  produced  to 
better  advantage  by  a triple  lantern,  and  without  going  into  the 
consideration  of  many  elaborate  examples  of  such  slides  and  effects 
as  can  only  be  shown  by  a triple  lantern,  we  will  illustrate  a simple 
instance  with  such  an  effect  as  nearly  every  lanternist  will  be 


THE  TRIPLE  LANTERN. 


6 — 2 


78 


THE  MAGIC  LAN  TEEN  MANUAL. 


acquainted ; for  instance,  the  Mosque  of  Omar.  This  usually  con- 
sists of  three  slides  ; No.  i,  the  Mosque  by  daylight;  No.  2,  the 
Mosque  by  night ; and  No.  3,  the  effect  to  be  used  in  conjunction 


Eig.  55- 


with  No.  2 for  illuminating  the  stained  glass  windows  from  within, 
and  often  in  this  slide  the  moon  is  made  to  appear.  We  will  first 
see  what  Can  be  done  with  these  in  a biunial  lantern.  No.  1 slide 


BEECHEY'S  LANTERN. 


79 


is  shown  by  the  first  lantern ; No.  2 slide  with  the  second  lantern. 
Next  we  will  bring  out  the  illumination  of  the  windows  with  the 
first  lantern,  and  to  increase  the  effect  of  night  we  lower  the  light 
on  No.  2 ; and  if  the  moon  is  to  be  shown  with  No.  3,  we  produce 
a superior  light  upon  it.  Up  to  now  the  effect  is  splendid ; but 
here  comes  in  the  difficulty.  How  are  we  to  get  the  next  subject 
on  the  screen,  for  we  must  remember  both  lanterns  are  engaged  ? 
Why,  there  is  only  one  way,  and  that  is  to  take  away  the  light  from 
the  stained  glass  windows,  and  put  out  the  moon,  by  raising  the 
light  on  No.  2 slide  to  get  away  No.  3 for  the  next  picture.  Now, 
in  the  triple  arrangement,  we  should  leave  the  effect  as  it  stood, 
and  introduce  the  next  subject  in  the  third  lantern,  dissolving 
away  Nos.  2 and  3 at  the  same  time.  For  other  illustrations  see 
page  1 18.  See  also  description  of  curtain  roller  slide  for  exhibiting 
statuary,  page  121. 


BEECHEY’S  LANTERN. 

UP  to  the  present  time  dissolving  views  have  been  treated  of 
as  being  produced  by  two  or  three  lanterns,  or  with  one 
lantern  arranged  with  two  or  three  separate  lights.  An  idea  for 
producing  the  above  effect  with  one  only,  emanated  from  the  Rev. 
Canon  Beechey,  who  many  years  ago  had  a lantern  constructed 
in  which  only  one  light  was  used  to  illuminate  three  distinct 
optical  systems,  and  for  the  purpose  of  producing  dissolving  views 
and  other  dioramic  effects.  This  lantern  was  first  exhibited  at  the 
Exhibition  of  1851,  and  is  here  illustrated  at  Fig.  56. 

It  consists,  as  shown  in  the  diagram,  of  three  separate  optical 
systems  emanating  from  one  body,  with  prisms  placed  at  the  ex- 
tremities of  the  side  systems,  which  were  placed  at  such  angles  that 
the  discs  from  all  three  were  concentric  on  the  screen.  The  first 


produce  dissolving  views,  but  also  to  have  all  three  systems  in 
operation  at  the  same  time  when  required  for  effects,  &c.,  he  there- 
fore discarded  the  cylinder  form  of  lime  and  substituted  the  sphe- 
rical, which  was  suspended  by  a platinum  wire  over  the  flame  of  a 
fountain  oil  lamp,  through  the  centre  of  which  passed  a gentle 
stream  of  oxygen.  The  whole  of  the  lower  portion  of  the  lime 
was  thus  rendered  luminously  incandescent,  and  the  rays  of  light 
collected  by  each  system  thus  equalized.  The  oxygen  nozzle 


80  THE  MAGIC  LANTERN  MANUAL. 


illuminating  power  used  was  the  oxy-hydrogen  lime  light,  the 
cylinder  form  of  lime  being  used,  and  which  was  supported  upon 
a pin,  this  pin  being  fixed  central  with  all  three  condensers.  An 
unequal  light  was  the  result,  the  side  systems  receiving  less  than 
the  centre  one.  As  it  was  the  inventor’s  intention  not  only  to 


KE EVILS  LANTERN, , 


Si 


being  of  large  size,  little  pressure  was  needed,  and  therefore  the 


sures  had  been  used.  Although  this  oxy-calcium  light  was  much 
inferior  to  oxy-hydrogen,  it  proved  very  successful  for  small-sized 
discs.  A very  perfect  mechanical  dissolver  was  attached,  and  the 
whole  arrangement  so  simple  and  unique  that  we  cannot  but  ex- 
press surprise  that  the  principle  so  long  remained  in  statu  quo . 

This  same  idea  of  dissolving  with  one  light  has  been  adopted 
by  M.  Duboscq,  of  Paris,  substituting  the  electric  for  the  lime 
light.  In  Duboscq’s  apparatus,  both  sets  or  lenses  were  placed 
as  close  together  as  possible  with  convenience,  and  parallel  to 
each  other ; a concave  reflector  being  arranged  to  throw  the  light 
to  each  condenser  alternately,  while  a very  simple  sliding  dis- 
solver opened  and  closed  the  objectives. 


MOTHER  form  of  dissolving  lantern  made  its  appearance  a few 


years  ago,  based  upon  the  original  idea  of  Canon  Beechey’s 
(namely,  dissolving  with  one  light),  and  which  was  styled  “KeeviPs 
Patent  Newtonian  Lantern,”  illustrations  of  which  are  shown  at 
Figs.  57  and  58.  It  is  duplex  in  form,  being  fitted  with  one  optical 
system,  projecting  in  front,  shown  at  a,  and  another  projecting  from 
one  side,  as  shown  at  b.  The  light  through  the  system  a is  trans- 
mitted on  to  the  screen  direct,  in  the  usual  way.  At  the  extre- 
mity of  the  system  b is  fixed  a prismatic  lens,  by  which  means  a 
disc  can  be  projected  on  to  the  screen,  central  with  the  one  from 
a.  The  oxy-hydrogen  jet  is  arranged  on  a pivot,  which  is  a fixture 


lime  was  not  so  liable  to  split,  as  if  a small  nozzle  and  heavy  pres- 


KRBVIL’S LANTERN. 


32 


THE  MAGIC  LANTERN  MANUAL. 


in  the  bottom  of  the  lantern,  the  centre  of  rotation  being  as  near 
the  outside  surface  of  the  lime  cylinder  as  possible;  and  by 
rotating  the  burner  through  about  a quarter  of  a circle,  the  light 
is  brought  central  with  each  condenser  alternately,  and  simul- 
taneously the  me- 
chanical dissolver 
(c  c)  opens  and  closes 
the  objectives.  To 
compensate  for  any 
loss  of  light  occa- 
sioned by  the  use  of 
the  prism,  the  con- 
Fig.  57.  denser  of  this  system 

is  made  somewhat  shorter  in 
focus  than  the  other  one, 
evenness  of  illumination 
being  thereby  secured.  Both 
objectives  are  made  achro- 
matic, and  the  definition  of 
the  one  to  which  the  prism 
is  attached  is  very  little  infe- 
rior to  the  ordinary  one.  The 
jets  never  require  adjustment, 
as  each  lantern  is  put  to  a practical  test  before  being  sent  out ; the 
best  position  for  the  jet  being  thereby  obtained,  further  adjustment 
becomes  unnecessary.  The  dissolving  apparatus  is  adjustable  and 
fairly  efficient.  The  conical  fronts  are  easily  detached,  and  if  re- 
quired it  can  be  used  as  a single  lantern. 

Its  small  dimensions  are  much  in  its  favour,  the  whole  packing 
into  a small  box,  easily  carried  in  the  hand. 


THE  OPAQUE  LANTERN, 


83 


THE  OPAQUE  LANTERN. 

MAGIC  Lantern  pictures  are  called  Transparencies  because 
they  are  shown  by  light  transmitted  through  them ; but 
a very  wide  range  of  opaque  subjects  can  be  exhibited  upon  the 
screen,  and  made  highly  interesting,  by  an  instrument  introduced 
first  in  a practical  form  by  Messrs.  Chadburn,  in  which  photographs, 
cartes-de-visite,  engravings,  drawings,  and  other  opaque  objects, 
such  as  minerals,  crystals,  shells, 
plaster  casts,  medals,  cameos, 
coins,  small  flowers,  watches  in 
motion,  the  human  hand  and 
face,  and  an  infinite  variety  of 
subjects,  may  be  exhibited  with 
their  natural  colours  and  shades. 

Its  construction  (see  Fig.  59) 
consists  of  a lantern  box,  in 
which  is  fixed  a pillar  to  which 
the  lime-cylinder  is  attached, 
and  behind  it  is  a large  silvered  reflector,  accessible  for  adjustment, 
which  can  be  raised  or  lowered,  moved  backwards  or  forwards ; 
the  light  it  receives  being  thrown  upon  the  condenser,  and 
thereby  concentrated  upon  the  picture  or  object  placed  in  the 
sliding  door  of  the  angular  box  which  joins  up  to  the  square 
compartment.  The  illuminated  picture  or  object  is  then  received 
by  the  achromatic-objective,  and  projected  upon  the  screen.  The 
angular  compartment  can  be  detached  and  replaced  with  ordi- 
nary lantern  fronts,  and  direct  light  with  transparent  pictures  can 
be  used.  The  half  of  an  orange,  if  squeezed  and  placed  in  this 
lantern,  has  a particularly  grotesque  effect. 


84 


THE  MAGIC  LANTERN  MANUAL. 


A convenient  adaptation  to  the  ordinary  lantern  has  been 
designed  and  manufactured  for  exhibiting  opaque  objects,  styled 
the  “ Aphengescope.”  These  are  made  suitable  for  both  single 
and  double  lanterns,  the  latter  one  giving  the  better  results.  It 
may  be  described  as  a box  hexagonal  in  shape,  two  sides  of 
which  are  provided  with  holes  to  receive  the  lights  from  the  two 
lanterns,  the  objectives  having  been  removed.  On  an  interme- 
diate side,  between  those  in  which  the  holes  are  made,  is  fixed 
an  objective,  and  at  the  side  opposite  this  objective  the  objects 
to  be  shown  are  placed ; thus  it  will  be  noticed  that  the  lanterns 
themselves  are  fixed  with  their  backs  opposite  the^screen,  the  light 
from  both  being  united  and  concentrated  to  illuminate  the  object. 
On  account  of  the  great  loss  of  light  by  reflection,  large  exhibitions 
with  this  adaptation  should  not  be  attempted. 


USEFUL  and  convenient  Stand  for  the  Lantern  is  illus- 


trated at  Fig.  60.  It  consists  of  a tripod  made  of  either 
ash  or  oak,  upon  which  is  fixed  a board  to  which  the  lantern 
is  attached.  It  possesses  great  steadiness,  and  is  capable  of 
adjustment  to  work  at  any  height  or  angle,  to  suit  the  operator. 
In  many  instances  it  is  desirable  to  have  the  lantern  elevated 
to  a considerable  height  from  the  floor,  so  as  to  bring  the  centre 
of  the  lantern  in  line  with  the  centre  of  the  screen.  Thus,  in 
showing  a picture  12  feet  in  diameter,  the  bottom  of  which 
should  not  be  less  than  2 feet  from  the  ground,  the  centres  of  the 
lantern  would  require  to  be  8 feet  from  the  floor.  This  tripod  is 


STAND  FOR  THE  LANTERN. 


STAND  FOR  THE  LANTERN. 


85 


made  when  required  with  a ball-and-socket  joint,  placed  between 
the  flat  table  top  and  the  top  of  tripod,  also  with  other  accessories 


Fig.  60. 


suitable  for  the  photographer  in  supporting  large  cameras.  It  may 
also  be  adapted  as  a stand  for  supporting  a telescope. 


86 


THE  MAGIC  LANTERN  MANUAL. 


SCREENS. 

IF  a place  can  be  assigned  for  a permanent  Screen,  nothing 
can  surpass  a whitened  wall,  which  may  be  ornamented  with 
drapery,  or  by  a pair  of  Corinthian  columns.  These  latter  can  be 
purchased  at  the  decorator’s  or  paper-hanger’s,  printed  in  colour ; 
and  when  varnished  and  fixed  at  each  side  of  the  screen,  over 
the  top  of  which  a suitable  inscription  should  be  placed,  forms  an 
embellishment  at  a small  outlay.  By  making  a dead  black  border 
of  some  inches  in  width  to  the  white  screen,  the  pictures  shown 
may  overlap  the  border  without  being  noticed,  and  thus  every  pic- 
ture may  be  made  to  appear  as  registering  absolutely. 

In  the  case  of  Portable  Screens,  as  the  best  results  are  to  be 
derived  from  opaque  ones,  screens  of  this  class  may  be  obtained 
up  to  io  feet  square,  made  of  cloth,  faced  with  white  paper  having 
an  ornamental  border,  the  whole  mounted  upon  a roller.  This  is 
a very  convenient  form,  and  is  easy  to  erect ; but  beyond  the  above 
dimensions  they  are  altogether  out  of  the  range  of  portability. 
Those  next  in  quality  are  of  linen ; these  also  can  be  had  up  to 
10  feet  square,  having  no  seams.  As  it  is  very  objectionable  to 
have  a seam  running  down  the  centre  of  a screen,  if  a large  one 
is  required,  it  should  be  made  by  joining  two  pieces  outside  one 
wide  width,  so  that  the  centre  portion  is  free  from  piecings.  A 
method  adopted  by  the  author  for  suspending  linen  screens  of 
large  dimensions  in  school-rooms,  is  to  fix  iron  staples  in  the  wall 
near  to  the  ceiling,  and  also  near  to  the  floor.  The  screen  being 
provided  all  round  its  edges  with  loops  of  tape,  a sash-cord  of 
suitable  strength  is  threaded  through  the  loops  and  also  through 
the  staples,  whereby  the  whole  is  stretched  perfectly  tight  and 
even.  A length  of  fringe  attached  to  the  top,  with  a little  drapery 


SCREENS. 


8/ 


hanging  down  either  side,  gives  a neat  appearance  without  much 
trouble  or  cost. 

A convenient  form  of  portable  frame  for  screens  up  to  1 2 feet 
is  shown  at  Fig.  61.  The  frame  is  put  together  in  the  manner  of 
a fishing-rod,  and  can  be  erected  at  private  entertainments,  without 
having  to  disturb  furniture,  etc.,  in  an  incredibly  short  time.  It 
is,  moreover,  capable  of  being  packed  in  a very  small  compass ; 
another  advantage  being  that  it  can  be  used  as  a Transparent  Screen 


when  occasion  requires,  the  audience  being  placed  on  the  oppo- 
site side  to  the  lantern ; but  it  should  be  remembered  that  by  adopt- 
ing this  plan  the  result  is  never  so  good  as  with  an  opaque  screen. 

Transparent  screens  can  be  made  of  thin  cotton  sheeting,  or, 
what  is  still  better,  of  muslin.  Before  using  they  should  be  well 
wet  with  water ; best  applied  after  the  screen  is  erected,  by  means 
of  a garden  syringe.  This  wetting  makes  the  surface  more  homo- 
geneous and  transparent.  A neat  screen  for  exhibiting  microscopic 
objects  was  constructed  by  the  author,  out  of  a child’s  wooden 
hoop  about  three  feet  in  diameter,  covered  with  tracing-paper,  pre- 
viously moistened,  and  then  glued  to  its  periphery.  On  becoming 
dry,  it  presented  a beautifully  even  surface,  and  as  tight  as  a drum. 


Fig.  61, 


88 


THE  MAGIC  LANTERN  MANUAL. 


By  screwing  a stick  to  the  rim  of  the  hoop  it  can  be  held  in  posi- 
tion, and  regulated  for  height  by  tying  to  the  back  of  a chair,  or 
it  may  be  fixed  in  the  bottom  portion  of  a photographer’s  head- 
rest stand.  Statuary  exhibited  upon  this  screen  has  a charming 
effect. 


LANTERN  SLIDES. 

THE  production  of  Photographic  Magic  Lantern  Slides  has 
been  taken  up,  commercially,  by  some  very  enterprising 
firms  in  England,  France,  and  America,  the  result  being  that  com- 
plete series  of  views,  at  wonderfully  low  prices,  are  to  be  obtained, 
not  only  of  our  dear  old  country,  but  also  of  our  much-prized  India, 
the  land  of  the  Pharaohs,  of  the  Holy  Land,  of  the  Alpine  scenes 
of  Switzerland,  of  the  ruins  of  sunny  Italy,  of  the  bygone  splendour 
and  greatness  of  Spain,  of  the  natural  wonders  of  the  Far  West,  of 
the  Polar  regions,  of  the  Tropics ; and  even  the  bowels  of  the  earth 
have  been  photographed,  as  have  also  the  fantastic  and  ever-chang- 
ing forms  of  aerial  grandeur ; whilst  portraits  of  the  sun,  with  the 
vast  protuberance  surrounding  his  edge,  and  the  dark  spots  which 
travel  across  his  face,  together  with  eclipses,  our  satellite  in  all  her 
phases,  and  the  spectra  of  other  heavenly  bodies,  though  yet  so  far, 
are  brought  so  near ; and  the  most  minute  details  of  insects  and 
objects  invisible  to  the  unaided  eye  are  produced  in  magnified 
dimensions  with  that  correctness  to  which  no  living  artist  can  as- 
pire. On  looking  at  a photograph,  we  feel  sure  that  we  have  a 
faithful  representation  of  the  subject,  for  the  photographer  has 
neither  the  power  to  add  nor  to  detract  from  his  subject.  He 
must,  therefore,  choose  his  point  of  sight  with  the  skill  which  de 
notes  the  difference  between  a mere  photographer  and  one  who 
combines  art  with  his  profession. 


LANTERN  SLIDES . 


89 


The  photographic  transparencies  in  carbon,  and  known  as  the 
“ Woodbury  Lantern  Slides,”  are  among  the  finest  ever  produced. 
The  process  of  their  production  admits  of  any  colour,  perhaps 
none  more  beautiful  than  the  warm  chocolate,,  for  which  these 
slides  have  obtained  a world-wide  reputation.  They  are  printed 
from  the  choicest  negatives  of  the  most  eminent  photographic 
artists  in  the  world : thus  almost  every  slide  in  the  long  list  pub- 
lished by  the  Sciopticon  Company  may  be  relied  upon  as  a photo- 
graphic gem.  The  shadows  and  darker  portions  are  of  a more 
transparent  colour  than  in  slides  of  which  silver  usually  forms  the 
deposit ; thus  more  light  is  allowed  to  pass  through,  and  a more 
brilliant  picture  obtained  on  the  screen.  These  slides  are  made 
inches  long  by  3^  deep,  with  a neat  mount  bearing  the  name 
of  the  subject,  or,  if  desired,  they  are  supplied  3!  inches  square 
(the  English  standard  size). 

The  productions  of  Messrs.  F.  York  and  Son  merit  special 
praise.  This  firm  devote  themselves  almost  exclusively  to  lantern 
slides,  and  are,  perhaps,  the  largest  producers  in  the  world.  Their 
pictures  of  the  animals  in  the  collection  of  the  Royal  Zoological 
Society  are  really  wonderful.  The  architectural  views  of  London, 
and  the  more  recent  pictures  of  Paris  and  its  Exhibition,  are 
characteristic  of  the  greatest  ability.  York’s  slides  are  produced 
by  the  wet  collodion  process,  and  toned  with  platinum,  and  there- 
fore may  be  relied  upon  for  permanency.  They  are  of  uniform 
size,  3|  inches  square,  with  circular  mounts,  having  an  aperture 
inches  in  diameter.  Messrs.  York  print  their  slides  up  to  the 
edges,  thus  giving  the  opportunity  to  those  who  would  prefer  to 
substitute  any  other  shape  of  mount,  square,  cushion-shaped,  or 
dome.  On  the  edge  of  each  slide  is  a printed  label,  bearing  the 
title  of  the  picture. 

Messrs.  Wilson,  of  Aberdeen,  and  Messrs.  Valentine,  of 


90 


THE  MAGIC  LANTERN  MANUAL. 


Dundee,  have  always  ranked  amongst  the  highest  class  lantern 
slide  producers;  within  the  past  few  years,  however,  their  business 
in  this  speciality  has  been  so  considerably  augmented  that  special 
attention  has  been  given  to  the  subject,  improvements  have 
suggested  themselves,  and  now  there  are  very  few  slides,  if  any, 
that  can  excel  those  of  Valentine’s  or  Wilson’s. 

Mr.  William  England,  whose  fame  is  world  wide  known,  has 
produced  some  of  the  finest  lantern  slides  ever  exhibited,  and 
the  perfection  of  his  Statuary  Slides  is  unsurpassed. 

The  French  Slides  of  M.  Levy  (late  Ferrier  and  Co.)  and 
Messrs.  Lachenell,  of  Paris,  have  long  held  a reputation  for 
excellence ; unlike  most  English  Slides,  these  are  produced  on 
albumen  dry  plates,  the  exact  formula  of  their  production  long 
being  kept  a secret. 

It  is  supposed  they  were  toned  with  sulphur,  which,  although 
it  produces  a most  agreeable  tone,  is  not  always  permanent. 
Photographs  treated  in  this  manner  have  been  known  to  fade  in 
a moderately  short  time,  and  leave  behind  but  a shadow  of  their 
former  beauty.  The  above  firms  have  produced  of  late  years 
many  excellent  lantern  slides ; and  as  Stereoscopic  Transparencies, 
it  is  much  to  be  deplored,  have  not  been  so  much  in  request  as 
formerly,  perhaps  lantern  slides  may  have  occupied  more  of  their 
attention. 

A good  stereoscopic  slide  does  not  always  make  a good  lantern 
slide,  as  the  latter  usually  requires  less  printing  than  is  suitable  for 
the  stereoscope. 


PRODUCTION  OF  PHOTOGRAPHIC  SLIDES.  gf 

PRODUCTION  OF  PHOTOGRAPHIC 
SLIDES. 

LT HOUGH  there  are  many  lanternists  who  are  also  pho- 


tographers, there  are,  perhaps,  many  who  dread  entering 
into  that  art  which  brings  up  visions  of  soiled  fingers,  spoiled 
clothes,  dark  rooms  filled  with  a mass  of  apparatus  and  bottles 
enough  to  fill  a museum  or  chemist’s  shop,  with  unlimited  expen- 
diture. To  such  readers  it  may  be  well  to  give  a few  details  on 
the  Production  of  Photographic  Slides,  so  as  to  banish  from  their 
minds  all  these  ideas.  Nowadays  photography  need  not  be  made 
the  expensive,  laborious,  and  tedious  art  of  the  past.  Modern 
improvements  have  placed  it  in  the  power  of  almost  every  tourist 
to  become  a photographer,  and  for  the  production  of  lantern  trans- 
parencies the  whole  apparatus,  including  pocket  camera,  chemicals, 
dry  plates,  &c.,  may  be  kept  in  a box  or  cupboard,  no  dark  room 
being  absolutely  necessary,  as  all  operations  requiring  the  exclu- 
sion of  daylight  can  be  performed  in  the  evening.  However,  as 
this  treatise  does  not  admit  of  a full  description  of  photography, 
we  will  suppose  the  reader  to  have  acquired  some  knowledge  of 
the  art  from  one  of  the  many  excellent  modern  works  published 
on  the  subject,  and  merely  give  an  outline  of  a lengthened  ex- 
perience in  the  production  of  lantern  transparencies.  These  may 
be  produced  in  several  ways,  by  wet  collodion,  dry  collodion, 
albumen,  or  gelatine  dry  plates,  and  also  by  the  carbon  pro- 
cess. 

To  reply  to  the  question,  “ Which  is  the  best  process  for  making 
lantern  transparencies  ? ” would  be  very  difficult,  as  circumstances 
and  conditions,  and  the  skill  or  experience  of  the  operator,  has 
much  to  do  with  the  matter.  Perhaps  the  simplest  plan  for  an 


7 


92 


THE  MAGIC  LANTERN  MANUAL. 


amateur  is  to  print  them  upon  gelatino-bromide  plates,  sold  com- 
mercially by  many  firms  who  make  a speciality  of  transparency 
plates,  and  supply  the  formula  for  developing  same. 

COLLODIO-BROMIDE  EMULSION  PROCESS, 

as  published  by  Mr.  Wm.  Brooks,  is  a favourite  for  amateurs  who 
wish  to  produce  the  best  results  with  little  trouble. 

“ Cleaning  the  Plate. — In  my  own  practice  for  very  many  years  I 
have  never  used  anything  for  polishing  the  plate  but  methylated 
spirit.  Before  polishing,  if  the  plates  are  dirty,  I pass  them  through 
a hot  bath  of  common  washing  soda,  not  allowing  them  to  remain 
there  longer  than  to  soften  and  remove  the  dirt,  old  films,  varnish, 
&c.  A few  minutes’  immersion  I find  quite  sufficient ; they  are 
then  taken  out  singly  and  washed  rapidly  under  the  tap,  rubbing 
either  with  the  fingers  or  a pad  of  rag,  and  freed  from  the  soda 
solution  as  quickly  as  possible;  for  if  any  remains  on  the  plate 
after  drying,  it  is  like  so  much  grease,  and  rather  difficult  to  get 
rid  of.  I never  on  any  account  use  any  of  the  mineral  acids  for 
cleaning  plates,  as  I am  sure  they  cause  the  film  to  slip,  which  is 
very  troublesome.  After  the  plates  are  dry,  I rub  over  them 
methylated  spirit,  as  before  stated,  and  polish  with  a dry  chamois 
leather  kept  expressly  for  the  purpose.  The  plates,  when  polished, 
are  taken  singly  on  a pneumatic  holder,  and  edged  with  indiarubber 
to  the  depth  of  about  one-eighth  of  an  inch  all  round;  for  this 
purpose  I cut  a camel-hair  brush  ‘ stumpy  ’ with  a pair  of  scissors, 
and  tie  a narrow  slip  of  glass  about  an  eighth  of  an  inch  wide  on 
the  side  of  it,  allowing  it  to  project  a little  below  the  hairs;  this 
acts  as  a guide.  The  indiarubber  solution  is  made  by  dissolving 
the  rubber  in  benzole. 

“ Coating  the  Plate. — The  plate,  when  the  edging  is  dry,  is  taken 
on  a pneumatic  holder,  and  the  emulsion  poured  on  from  a bottle 


PRODUCTION  OF  PHOTOGRAPHIC  SLIDES.  93 


slowly  and  steadily,  and  the  surplus  poured  off  from  one  corner, 
and  then  set  up  to  dry.# 

“ Exposing  the  Plate. — Undoubtedly  the  best  results  are  obtained 
from  small  negatives  exposed  in  contact;  for  lantern  slides  quarter- 
plate  negatives  are  of  very  convenient  size.  The  negative  is  placed 
in  an  ordinary  printing  frame,  with  rather  weak  springs,  the  emul- 
sion plate  (3!  x 3!)  carefully  laid  on  the  negative,  the  back  board 
placed  in  position  under  pressure  of  the  springs.  Great  care  must 
be  taken  that  there  is  no  grinding  motion,  or  the  film  is  at  once 
spoiled  ; the  pressure  must  be  direct.  In  summer  time,  in  diffused 
light,  with  an  ordinary  quality  of  printing  negative,  about  one 
second  exposure  will  be  found  sufficient ; if  the  negative  be  dense, 
yellow,  or  green,  the  exposure  has  to  be  prolonged ; a little  prac- 
tice is  the  best  guide.  If  cold  tones  are  required,  short  exposure 
must  be  given,  and  longer  exposures  if  warm  tones  are  desired. 

“ The  exposure  can  be  made  in  the  camera  by  transmitting  light 
in  the  ordinary  way,  when  the  image  requires  to  be  reduced  from 
a large  negative.  To  get  the  best  result,  the  apparatus  should  be 
pointed  to  the  sky ; if  the  sun  be  shining,  a piece  of  ground  glass 
placed  a few  inches  from  the  negative,  to  keep  the  texture  of  the 
glass  out  of  focus,  is  all  that  is  required.  An  exposure  made  in 
this  way  in  a good  average  light  may  be  from  one  minute  upwards. 

u Development.— After  the  plate  has  been  exposed,  methy- 
lated alcohol  is  poured  over  its  surface  and  allowed  to  soak 
for  one  minute ; care  must  be  taken  not  to  use  the  alcohol 
too  strong,  but  it  should  be  employed  as  strong  as  the  film  will 
allow,  say,  about  840.  sg.  The  plate,  after  flooding  with  the 
alcohol,  is  placed  in  water.  I generally  use  a basin— about  half 
a gallon  size — and  drop  the  plate  in  face  downwards ; the  con- 

* The  Washed  Collodio- Bromide  Emulsion  may  be  made  by  many  of  the  pub- 
lished formulas,  or  purchased  from  Mr.  Brooks. 


7—2 


94 


THE  MAGIC  LANTERN  MANUAL. 


vexity  of  the  basin  does  not  allow  the  film  to  be  injured  in  any 
way.  While  the  alcohol  is  soaking  out,  the  developer  can  be  pre- 
pared, but  before  the  latter  is  applied,  the  plate  must  be  well 
washed,  so  that  the  water  blends  with  the  film,  or  the  development 
will  take  place  unevenly  and  in  patches.  There  are  many  ways 
of  accomplishing  the  development.  * will  first  give  the  solu- 
tions : — 

Solution  P. 

Pyrogallic  acid  . . . . .96  grains. 

Absolute  alcohol  ......  1 ounce. 

Five  minims  of  the  above  will  contain  one  grain  of  pyrogallic  acid. 


Solution  A. 

Carbonate  of  potassium 
Bromide  of  potassium  . 

Acetate  of  soda  .... 

Water  ...... 

“ Into  a clean  developing  measure  put — 
Solution  P.  .... 

Solution  A. 

Water ...... 


300  to  360  grains. 

• 60  „ 

120  „ 

. . 12  ounces. 

10  to  20  minims. 

2 drachms. 
. 2 


This  is  at  once  poured  over  the  plate  as  soon  as  it  is  washed  free 
from  the  alcohol. 

“To  obtain  different  ranges  of  tone  I use,  as  will  be  seen,  ace- 
tate of  soda,  but  I do  not  always  keep  to  that  salt  alone  for  the 
purpose,  as  various  others  can  be  used  with  advantage,  namely, 
phosphate  of  soda,  tungstate  of  soda,  acetate  of  potash,  citrate  of 
soda  and  also  of  potash,  and  various  others  of  a like  nature.  A 
few  drops  of  a freshly-prepared  saturated  solution  of  borax  added 
to  the  developer  gives  a very  pretty  tone.  This  solution  appears 
to  be  a very  powerful  restrainer,  so  must  be  used  with  caution,  but 
it  loses  its  power  if  more  than  a day  old. 


PRODUCTION  OF  PHOTOGRAPHIC  SLIDES. 


95 


“If  the  negative  is  weak  the  pyro  requires  to  be  increased;  if 
dense  and  hard,  it  requires  to  be  reduced. 

“I  always  use  cyanide  of  potassium  as  a fixing  agent — about  20 
grains  to  the  ounce,  or  thereabouts — as  it  is  more  easily  got  rid  of 
before  toning ; hpyo.  gives  no  end  of  trouble.  Should  the  image 
appear  too  dense  and  heavy  after  fixing,  and  before  toning,  I have 
ready  about  a To-grain  solution  of  cyanide,  with  about  one  drop  of 
nitric  acid  added ; this  reduces  the  image  very  readily  and  evenly. 

“ After  fixing  allow  to  soak  in  a dish  of  clean  water  for  about  a 
quarter  of  an  hour  or  more,  and  it  is  then  ready  for  toning,  which 
is  readily  accomplished  with  the  following  solution  : — 

Bichloride  of  platinum  ...  .1  grain. 

Nitric  acid  ......  1 minim. 

Water  .......  3 ounces. 

“ A white  porcelain  dish  is  best  for  this  purpose,  if  the  plate  has 
been  properly  exposed  and  developed.  Almost  any  tone  can  be 
obtained  as  easily  as  in  the  case  of  the  silver  print. 

“ Should  the  image  appear  thin,  it  can  easily  be  intensified  before 


toning  with — 

Pyro  . 

0 

• 

. 2 grains. 

Citric  acid  . 

. 

1 grain. 

Water 

. . 

c • 

1 ounce. 

“With  a drop  or  two  of  a 10-grain  solution  of  nitrate  of  silver 
added,  any  amount  of  intensity  can  be  obtained  in  this  way,  but 
care  must  be  taken  to  avoid  over-intensity.  I have  had  all  sorts 
of  toning  agents,  but  I find  none  of  them  to  equal  platinum.” 

TANNING  PROCESS. 

In  this  process  a substratum  is  necessary  to  prevent  the  film  from 
slipping  off  the  plate  during  development.  The  following  formula 
may  be  used  without  the  necessity  of  polishing  the  plates ; these 


96 


THE  MAGIC  LANTERN  MANUAL. 


after  being  well  washed  under  a tap,  should  be  slightly  drained, 
and  while  still  wet  flowed  over  with 

Albumen  (white  of  egg)  . . . . i ounce. 

Water  i pint. 

Liquid  ammonia  . . . . .15  drops. 

This  must  be  well  shaken,  either  by  means  of  an  egg-beater,  or 
in  a bottle  with  some  broken  glass,  and  must  be  well  filtered  pre- 
vious to  using.  After  drying  over  a hot-water  plate  or  before  the 
fire,  and  allowed  to  cool,  the  plates  are  ready  to  receive  the  collo- 
dion, almost  any  good  sample  of  which  will  do,  preferably  rather 
thick.  Use  an  ordinary  45 -grain  silver  bath,  rather  acid.  After 
exciting  the  plate,  wash  well  under  a tap,  and  while  wet  apply  the 
preservative  solution,  consisting  of 

Tannin  . . . . 0 . .15  grains. 

Water  1 ounce. 

Sugar.  .......  5 grains. 

This  must  be  fresh  mixed  and  well  filtered. 

The  first  application  should  be  cast  away,  and  a second  applied. 
Now  place  in  the  drying-rack.  The  exposure  is  made  by  placing 
the  plate  close  against  a negative,  the  two  film  sides  being  in  con- 
tact, any  ordinary  pressure  printing-frame  being  used.  The  time 
of  exposure  varies  according  to  the  density  of  the  negative,  and 
the  distance  and  nature  of  the  light.  However,  with  an  ordinary 
negative,  and  placed  some  6 inches  away  from  the  flame  of  an 
ordinary  gas-burner,  some  20  to  60  seconds  will  be  required. 

The  development  must  be  conducted  in  an  equally  non-actinic 
light  to  the  preparation.  First  moisten  the  film  by  flowing  over  it 
a solution  of  alcohol  and  water  in  equal  portions,  now  wash  well, 
and  the  developing  solution  may  be  applied. 

Pyrogallic  acid  . . . .3  grains  ■)..., 

\ mixed  fresh. 


Water 


1 ounce  J 


PRODUCTION  OF  PHOTOGRAPHIC  SLIDES.  97 


This  will  soon  cause  the  image  to  appear  if  the  exposure  has 
been  properly  timed;  and  when  sufficient  detail  is  manifest  re- 
develop with  same  solution,  with  the  addition  of  a few  drops. 

Citric  acid  . , 0 . 0 .30  grains. 

Nitrate  of  silver  „ . . 0 .20  grains. 

Water,  . ounces. 

This  will  soon  bring  the  picture  to  the  necessary  depth.  It 
should  now  be  washed  and  fixed  in 

Hyposulphite  of  soda  . . . . 1 ounce, 

Water  .......  6 ounces, 

when,  after  further  washing,  the  picture  is  finished,  and  should  be 
of  a good  warm  tone.  If  necessary,  it  may  be  toned  with  a weak 
solution  of  chloride  of  gold. 

MODIFIED  ALBUMEN  PROCESS. 

By  this  process  the  best  possible  results  can  be  obtained.  Take 
a good  bromo-iodized  collodion,  which  must  be  old  and  ripe,  and 
in  such  condition  that  as  soon  as  it  is  set  it  may  be  written  upon 
with  a pen  without  tearing  the  film.  After  coating  the  plate,  when 
set  it  must  be  immersed  in  water  for  a few  minutes,  and  then  well 
washed  under  a gentle  stream  from  the  tap.  Now  coat  with  albu- 
men as  follows  : — 

Albumen  (from  fresh  eggs)  . . .10  ounces. 

Acetic  acid  . . . . . i|  drams. 

Previous  to  mixing,  the  albumen  should  be  beaten  into  a froth. 
Stir  well  with  a glass  rod,  and  allow  to  stand  for  twelve  hours, 
then  strain  through  muslin  or  sponge,  and  add  40  drops  of  strong 
liquid  ammonia.  In  6 drams  of  water  dissolve  60  grains  of  iodide 
of  ammonium  and  10  grains  of  bromide  of  ammonium.  Now  add 
this  solution  to  the  filtered  albumen,  allow  this  to  soak  into  the 
film  for  a minute  or  two,  then  set  it  to  drain,  and  dry  in  a warm 


98 


THE  MAGIC  LANTERN  MANUAL. 


place.  To  excite,  the  plate  must  be  allowed  to  remain  forty  seconds 
or  not  more  than  a minute  in  a bath  made  as  follows : — 

Nitrate  of  silver i ounce. 

Distilled  water 8 ounces. 

Acetic  acid  ......  2 ounces. 

Now  rinse  the  plate  well  under  a tap  for  one  or  two  minutes, 
and  set  aside  to  dry.  When  dry,  the  back  of  the  plate  must  be 
coated  with  burnt  sienna  finely  ground,  with  a little  gum-water 
added. 

Exposure. — From  five  seconds  to  five  minutes,  depending  upon 
the  intensity  of  the  negative  and  the  quality  of  the  light. 

Development. — After  removing  from  the  printing-frame,  rinse 
the  plate  under  the  tap  and  clear  away  the  backing,  best  done 
with  a piece  of  spongy  india-rubber.  The  development  is  best 
conducted  in  a flat  dish,  which  may  be  made  of  a piece  of  ribbed 
glass  and  a well-varnished  wooden  frame,  and  need  not  be  much 

. 60  grains. 

2 ounces. 

. 20  ounces. 

. 10  grains. 

. 20  grains. 

. 1 ounce. 

Take  of  solution  P sufficient  to  cover  the  plate,  and  warm  it  in 
a beaker  to  about  140  degrees  Fahrenheit ; pour  this  over  the  plate, 
keeping  it  in  motion  for  about  a minute,  then  add  three  drops  of 
solution  S,  still  keeping  the  plate  in  motion.  In  a short  time  the 
shadows  will  begin  to  appear.  As  soon  as  they  are  visible  by  trans- 
mitted light,  wash  well,  and  gently  rub  and  polish  well  the  film 
with  a tuft  of  cotton  wool.  Now  proceed  with  P moderately  hot, 
and  add  a few  drops  of  S.  So  soon  as  the  required  density  is 


larger  than  the  plate  itself. 
[ Pyrogallic  acid 
Glacial  acetic  acid 
Water 
x Citric  acid 
f Nitrate  of  silver 
S i Water  . 


PRODUCTION  OF  PHOTOGRAPHIC  SLIDES \ 


99 


attained,  wash  well  and  again  polish  with  cotton  wool.  Fix  in 

Hyposulphite  of  soda  , .6  ounces. 

Water  . . . . „ i pint, 

to  which  must  be  added 

Chloride  of  gold 4 grains. 

Water  2 ounces. 

The  plate  must  remain  in  the  fixing  solution  fifteen  to  twenty 
minutes,  being  rocked  occasionally,  and  when  removed,  well 
washed. 

The  most  important  condition  to  the  success  of  this  process  is 
to  have  the  collodion  right,  and  although  the  iodides  and  bromides 
are  washed  out,  it  must  not  be  supposed  that  plain  uniodized 
collodion  will  answer  the  purpose.  The  plate  after  being  excited 
should  present  an  uniform  slight  blue  tinge  : if  of  a patchy  or  mot- 
tled appearance,  the  collodion  is  too  horny.  No  varnishing  will 
be  required. 

CARBON  TRANSPARENCIES. 


Perhaps  no  process  suits  the  requirements  of  the  amateur  better 
than  the  Carbon  Process  for  the  production  of  Lantern  Trans- 
parencies. A special  tissue  for  this  purpose  is  prepared  by  the 
Autotype  Company,  of  a dense  warm  black.  It  may  be  had  either 
sensitized  or  unsensitized,  and  in  the  latter  state  will  keep  for 
an  almost  indefinite  period.  The  method  of  sensitizing  is  as 
follows : — 

A solution  of  bichromate  of  potash  is  made  by  dissolving  one 
part  of  this  salt  in  twenty  to  thirty  parts  of  water.  This  is  poured 
into  a tin  dish,  and  the  tissue  immersed ’ face  downwards,  until  it 
becomes  perfectly  pliable  (care  being  taken  to  exclude  any  air- 
bubbles),  which  will  generally  take  thirty  or  forty  seconds,  but  in 
winter  as  much  as  two  minutes  may  be  requisite.  In  summer  it  is 
sometimes  requisite  to  keep  a piece  of  ice  in  one  corner  of  the  tin 


100 


THE  MAGIC  LANTERN  MANUAL. 


dish.  The  tissue  on  being  removed  is  placed  face  downwards  on  a 
sheet  of  glass,  which  may  be  previously  wetted  with  sensitizer.  A 
squeegee  is  now  passed  over  the  back  to  remove  all  excess  of  solu- 
tion taken  up  by  the  paper.  On  removing  from  the  glass  plate, 
the  tissue  will  be  found  to  present  an  uniformly  clear  surface.  It 
must  now  be  hung  up  to  dry.  As  much  depends  upon  the  drying, 
amateurs  whose  requirements  are  small  would  do  well  to  purchase 
the  tissue  ready  sensitized. 

The  glass  plates  on  which  the  transparency  is  to  rest  should  be 
prepared  by  coating  with 

Gelatine i ounce. 

Water io  ounces. 

Chrome  alum io  grains. 

This  must  be  caused  to  flow  over  like  collodion,  and,  if 
necessary,  be  guided  to  the  edges  of  the  plate  by  a glass  rod. 
The  plates  may  now  be  reared  up,  and  when  dry  are  ready  for 
use. 

These  will  keep  any  length  of  time,  so  they  may  be  prepared 
beforehand. 

To  Print. — A thin  black  paper  mask  must  be  placed  upon  the 
negative,  the  aperture  in  which  being  a little  less  than  the  glass 
plate,  and  to  include  as  much  of  the  picture  as  wished.  The  object 
of  this  mask  is  to  procure  what  is  termed  a “ safe-edge.”  The  sen- 
sitized tissue,  already  cut  to  the  size,  is  now  laid  upon  the  masked 
negative  and  printed  in  a pressure-frame.  A little  longer  exposure 
will  be  usually  required  than  would  be  necessary  with  sensitized 
albumenized  paper.  The  exposed  tissue  is  now  removed,  and  im- 
mersed face  down  in  a dish  of  cold  water.  It  will  immediately  curl 
up,  but  will  in  a few  seconds  li$  perfectly  flat  in  the  water.  At  this 
stage  slip  one  of  the  prepared  glasses  into  the  dish,  and  bring  its 
gelatinized  surface  directly  under  the  tissue ; draw  the  two  out  of 


PRODUCTION  OF  PHOTOGRAPHIC  SLIDES.  iqi 


the  water  together,  and  apply  the  squeegee  to  the  back.  As  many 
as  are  printed  may  be  treated  in  a similar  manner,  and  placed  one 
on  the  top  of  the  other  to  keep  them  flat.  The  underneath  one 
may  now  be  developed  by  placing  it  in  water  of  the  temperature 
of  80  to  90  degrees  Fahrenheit,  and  shortly  the  paper  forming  the 
backing  to  the  tissue  will  curl  away.  A dark  slimy  mass  will  now 
be  perceived  on  the  glass  plate,  and  by  gently  moving  the  plate  in 
the  warm  water  the  soluble  portions  will  clear  away,  leaving  the 
insoluble  portions  attached  to  the  glass  plate. 

Should  the  transparency  appear  too  light,  deficient  in  half-tone, 
and  without  depth  in  the  shadows,  it  is  a sign  of  under-exposure ; 
should  it  be  over-exposed,  it  will  be  dark  and  indistinct,  and  the 
gelatine,  of  which  the  tissue  is  formed,  difficult  to  dissolve  away, 
in  which  case  increase  the  temperature  of  the  water.  The  remedy 
for  under  or  over-exposure  is  decrease  or  increase  in  temperature 
of  the  water,  warmer  water  being  necessary  for  over-exposure, 
and  colder  for  under-exposure.  So  soon  as  sufficiently  developed, 
immerse  for  five  minutes  in  a bath  of 

Alum  .......  1 part. 

Water  . . . . . . .40  parts. 

Wash  well,  and  after  drying,  mount  in  the  usual  way.  Ordinary 
printing  negatives  are  more  suitable  for  carbon  printing  than  the 
thin  ones  often  used  in  transparency  printing. 

Should  the  prints  not  be  sufficiently  dark  or  vigorous,  they  may 
be  intensified  like  an  ordinary  wet  collodion  negative,  or  immersed 
in  a bath  of  protosulphate  of  iron  and  gallic  acid. 

Although  a fair  outline  of  the  process  is  here  given,  for  further 
particulars  the  reader  is  referred  to  the  “ Autotype  Company’s 
Manual,”  popular  edition,  or  to  the  excellent  publication,  “A 
Manual  of  the  Carbon  Process,”  by  Dr.  Paul  Liesegang,  translated 
from  the  German  by  Mr.  R.  B.  Marston, 


102 


THE  MAGIC  LANTERN  MANUAL , 


WET  COLLODION  PROCESS. 

Up  to  now  the  making  of  photographic  transparencies  for  the 
lantern  has  been  treated  upon  dry  plates,  or  such  as  can  be  exposed 
in  contact  with  the  negative,  and,  with  the  exception  of  the  carbon 
process,  all  the  operations  of  preparation,  exposing,  and  developing 
can  be  performed  in  the  evening,  therefore  no  dark  room  or  day- 
light being  absolutely  necessary.  But  in  the  wet  collodion  process 
a camera  and  lens  are  indispensable,  and  a dark  room  for  develop- 
ing, and  daylight  for  exposing,  essential.  There  are  many  modifi- 
cations of  the  wet  collodion  process,  but  the  one  to  be  described 
has  been  worked  out  specially  for  lantern  slides  by  Mr.  John  S. 
Pollitt,  of  Manchester,  who  has  succeeded  by  it  in  producing  some 
of  the  most  charming  results  ever  seen  on  the  screen,  and  at  a 
recent  exhibition  of  slides,  made  by  more  than  a dozen  different 
processes,  by  as  many  or  more  exhibitors,  the  wet  collodion  (by 
this  process)  bore  the  palm.  The  negative  to  be  copied  should  be 
soft  and  full  of  detail;  it  may  be  of  any  size,  those  of  large  size, 
say  12  by  io  inches,  being  as  convenient  as  stereoscopic  size.  A 
camera  and  lens  of  ordinary  construction  will  answer  the  require- 
ments. The  negative  may  be  fixed  in  a window,  with  a sheet  of 
white  paper  placed  on  a board,  adjustable  to  the  proper  angle  so 
as  to  reflect  a uniform  light  on  to  the  negative,  and,  unless  the 
negative  be  very  intense,  all  diffused  light  should  be  excluded 
from  the  front.  A good  bromo-iodized  collodion  should  be  used, 
which  is  better  for  being  old  and  ripe  and  not  too  heavily  iodized : 
if  thick,  it  should  be  diluted  with  ether  s.p.  7*25.  An  ordinary 
silver  bath  should  be  employed,  made  decidedly  acid  with  a drop 
or  two  of  glacial  acetic  acid.  Great  care  must  be  exercised  in 
focussing,  and  a small  stop  should  be  inserted  in  the  lens. 

To  develope  the  plate,  the  following  solutions  are  necessary, 


PRODUCTION  OF  PHOTOGRAPHIC  SLIDES.  103 


and  as  the  superiority  of  the  process  depends  almost  entirely  upon 
the  development,  care  must  be  exercised  and  exact  adherence  of 
the  formula  observed  : — 


\ In  a large  earthenware  jar,  add  one  ounce  of  sulphuric  acid 
to  three  ounces  of  water  (heat  will  be  generated.)  When 
cold,  add  one  ounce  of  the  best  gelatine  (Nelson’s.)  Allow 
this  to  swell  for  some  time,  after  which  place  the  jar  and  its 
contents  in  a warm  place  for  twenty-four  hours,  say,  at  a 
temperature  not  exceeding  100  degrees  Fahrenheit,  when 
A ■{  the  gelatine  will  be  found  dissolved.  Next  add  clean  iron 
filings  in  excess,  avoiding  any  application  of  heat.  At  this 
stage  allow  the  whole  to  stand  for  several  days,  then  add 
fifteen  ounces  of  a two-grain  (to  the  ounce)  solution  of 
acetate  of  soda.  The  whole  may  now  be  filtered  and 
bottled  for  future  use,  and  in  this  condition  will  keep  good 
indefinitely. 


To  thirty  ounces  of  water,  add  one  ounce  of  proto-sulphate 
of  iron  and  four  drachms  of  glacial  acetic  acid. 


To  develope  the  transparency  take  sufficient  (to  cover  the  plate) 
of  B solution  in  a glass  developing  cup,  and  add  a few  drops  of 
A solution  (the  quantity  of  A may  be  regulated  by  the  amount  of 
vigour  it  is  desired  to  produce  in  the  resulting  image),  flow  it  over 
the  plate  in  the  usual  way,  and  if  the  image  appears  quickly,  in- 
dicating full  exposure,  the  developer  should  be  poured  off,  and 
the  plate  exposed  for  a little  time  to  the  action  of  the  atmosphere 
in  the  dark  room,  which  if  the  exposure  has  not  been  overdone, 
brings  out  the  picture  with  great  brilliancy.  When  the  image  is  well 
out,  wash  thoroughly,  and  fix  with  cyanide  of  potassium. 

The  above  developer  acts  somewhat  slowly  compared  with  other 


* This  solution  will  keep  good  for  four  or  six  months,  but  not  longer. 


104 


THE  MAGIC  LANTERN  MANUAL. 


iron  developers,  but,  when  a suitable  ripe  collodion  be  used,  gives 
an  exceedingly  fine  deposit  of  reduced  silver  in  the  film,  and 
thus  the  picture  is  admirably  suited  for  enlargement  or  pro- 
jection. 

It  is  better  with  a view  to  clearness  and  brilliancy  to  expose 
fully,  and  so  cause  the  developer  to  act  as  quickly  as  possible.  If, 
however,  after  fixing,  the  image  is  found  to  lack  density,  the  plate 
must  be  washed  well  and  intensified  with  a three-grain  solution  of 
pyrogallic  acid,  acidulated  with  one  drachm  of  glacial  acetic  acid, 
and  a few  drops  of  a thirty-grain  solution  of  silver  nitrate. 

This  application  usually  produces  a beautiful  warm  tone,  well 
suited  to  lantern  transparencies. 

If  it  be  desired  to  tone  the  transparency,  so  as  to  darken  the 
colour  by  reflected  light,  a very  weak  solution  of  a mixture  of  gold 
chloride  and  potassium  chloride  applied  to  the  film,  will  produce 
the  desired  effect;  when  dry,  the  transparency  may  be  mounted 
without  varnishing,  but  if  a good  clear  coat  of  transparent  varnish 
can  be  applied,  without  streaks,  the  brilliancy  will  be  improved : 
however,  as  this  is  a part  where  many  amateurs  fail,  a thin  coating 
of  albumen  may  be  substituted. 


MOUNTING  OF  LANTERN  SLIDES. 


ANTERN  SLIDES  should  always  be  protected  by  a plain 


glass  in  front,  with  a paper  mount  between  the  glass  and 
the  picture  of  a suitable  shape, — either  round,  cushion- shaped,  or 
dome.  A good  plan  is  to  have  these  mounts  black  on  one  side 
and  white  on  the  other,  the  white  side  being  convenient  for  writing 
the  name  of  the  picture,  and  should  be  next  the  plain  glass,  so 
that  when  exhibiting  it  may  be  easily  seen ; thus  by  adopting  one 


MOUNTING  OF  LANTERN  SLIDES. 


105 


regular  system  of  placing  the  white  side  next  the  condenser  the 
pictures  will  always  appear  the  natural  way  on  the  screen.  This 
latter  is  important,  more  especially  in  the  case  of  a slide  which 
exhibits  a clock  or  a printed  sign.  The  mounts  for  the  purpose 
are  most  easily  cut  by  using  the  “ Photographic  Trimmer  ” 
(Fig.  62),  and  the  shapes  for  same  (Figs.  63,  64,  65,  and  66), 
which  latter  may  be  procured  in  a variety  of  forms  and  sizes. 
With  this  little  instrument  the  smallest  curves  and  circles  may 


Fig.  63.  Fig.  64.  Fig.  65.  Fig  66. 


be  cut  as  clean  and  sharp  as  possible  to  imagine,  the  only  instruc- 
tions necessary  being  to  keep  the  cutter  pressed  well  up  to  the 
inside  edge  of  the  mount,  and  with  one  sweep  to  go  round  the 
whole.  A sheet  of  zinc  forms  an  excellent  medium  for  cutting 
upon.  The  edges  of  the  slide  should  be  bound  with  paper,  the 
best  for  the  purpose  being  the  sort  in  which  needles  are  wrapped, 
and  known  commercially  as  “ needle  ” paper.  Gelatine  or  gum 
tragacanth  are  good  adhesive  mediums. 

The  old-fashioned  method  of  mounting  slides  in  wood  frames 
should  be  abolished,  as  not  only  is  the  expense  greater,  but  they 
take  up  much  more  room  for  storage,  and  are  less  portable ; more- 


lo 6 THE  magic  lantern  MANUAL. 

over,  unless  stopping-pieces  are  attached,  arranged  to  the  width 
of  the  slide  stage  of  lanterns  (which  unfortunately  are  not  always 
alike),  the  pictures  will  be  far  from  registering  on  the  screen; 
whereas,  by  dispensing  with  the  wood  frames,  no  greater  liability 
to  breakage  is  incurred,  and  they  may  be  used  by  means  of  a 
suitable  carrier  in  any  lantern,  by  this  means  giving  absolute  regis- 
tration. As  some  of  our  readers  may  not  understand  the  benefit 
of  correct  registration,  a few  words  on  the  subject  may  not  be  out 
of  place.  What  is  meant  by  correct  registration  is  that  when  dis- 
solving one  picture  away,  the  following  one  should  take  its  place 
identically,  and  without  any  alteration  in  the  margin  of  the  picture 
being  observed.  Let  us  take  the  picture  of  a landscape  in  sum- 
mer, in  which  a cottage,  trees,  etc.,  may  be  present,  dissolving 
into  one  of  the  same  subject  identically,  but  in  winter-time.  The 
two  should  be  so  dissolved  that  one  takes  up  the  place  of  the 
other  exactly,  the  transformation  being  effected  without  the  obser- 
vers becoming  aware  of  the  change  taking  place  until  the  effect 
is  actually  attained.  Should  the  registration  be  neglected,  the 
second  picture  most  probably  will  make  its  appearance  out  of 
place,  and  there  will  be  seen  a double  picture,  until  such  time 
as  the  operator  has  moved  the  slide  into  its  proper  place.  This 
shifting  of  slides  when  once  on  the  screen  mars  the  whole  effect, 
and  in  many  instances  has  the  writer  known  this  want  of  registra- 
tion to  spoil  what  would  have  been  an  enjoyable  entertainment. 


CARRIERS. 

IT  is  a pity  that  all  lantern  slide  producers  could  not  have  agreed 
upon  one  definite  size  as  a standard.  As  it  is,  some  make 
them  3-i  square,  others  \\  x 3^,  and  the  French  size  being  3!  x 3?, 


CARRIERS . 


107 


while  many  amateurs  make  the  slides  out  of  stereoscopic  plates 
cut  in  halves,  namely,  3f  x 3J.  All  seem  to  have  adopted  the  3I 
in  depth,  therefore  the  most  practical  form  of  Carriers  are  those 
in  which  the  pictures  are  slided  through.  Thus,  one  having  been 
placed  in  the  carrier,  a second  one  is  intro- 
duced, which  pushes  the  previous  one  into 
its  place ; a third  one  now  pushes  the 
second  into  position,  and  simultaneously 
projects  the  first  one  to  the  outer  end  of  the 
carrier,  so  that  it  may  be  removed.  The 
slideholder  shown  at  Fig.  67  is  intended  for 
pictures  to  be  passed  through  it  in  a pano- 
ramic fashion,  but  as  the  slides  are  carried 
on  a piece  of  tape  placed  round  two  small 
pulleys,  the  movement  is  apt  to  be  very 
unsteady;  moreover,  the  mounts  forming 
the  margins  of  the  pictures  in  passing  through  present  to  the  eye 
an  unseemly  black  patch,  increased  the  more  by  the  ends  of  two 
pictures  being  together. 

REGISTERING  CARRIER. 

A Registering  Carrier  was  some  time  ago  introduced  by  the 
author,  in  which  slides  of  all  the  usual  sizes  could  be  used  indis- 
criminately with  perfect  registration.  A description  of  the  same 
was  published  in  the  British  Journal  Photographic  Almanac,  and  is 
here  reproduced  (Fig.  68). 

“Some  time  ago  I went  to  an  exhibition  of  dissolving  views 
given  by  a friend.  He  had  a most  elaborate  apparatus  and  some 
good  views,  but  they  were  badly  exhibited.  The  first  picture  shown, 
after  being  set  in  position,  looked  very  well ; the  second  made  its 
appearance  some  two  or  three  feet  out  of  its  intended  position, 

8 


io8 


THE  MAGIC  LANTERN  MANUAL. 


and  had  to  be  moved  during  the  dissolving;  the  third  came  on 
similar  to  the  second,  considerably  out  of  place ; and  during  the 
whole  of  the  exhibition  the  pictures  had  to  be  adjusted  during 
dissolving.  Sometimes  there  would  be  a round  picture,  then  a 
cushion-shaped,  and  afterwards  a dome,  causing  an  everlasting 
shifting  about,  which,  added  to  the  noise  of  the  carriers  being  re- 


moved and  replaced  in  the  lanterns,  very  much  detracted  from 
the  enjoyment  of  the  evening.  I was  quite  disappointed  at  the 
management  of  my  lantern  friend.  At  the  close  of  the  exhibition 
I remarked,  ‘You  ought  to  register  your  pictures  better  on  the 
screen.’  He  seemed  to  make  light  of  the  matter,  therefore  I in- 
vited him  to  spend  an  evening  with  me,  and  I would  show  him 
how  I obtained  a far  better  result  with  much  less  noise  and  trouble. 
On  the  appointed  evening  my  friend  arrived,  and  after  a little 
refreshment  we  retired  to  the  room  where  I usually  exhibit  my 
lanterns.  In  a few  minutes  I had  my  Sciopticons  at  work,  using 
oil. 

“‘What  a splendid  light  you  get!’  said  my  friend.  ‘I  have 


Fig.  68, 


CARRIERS. 


109 


never  seen  so  good  a light  before  with  the  same  apparatus.  How 
do  you  produce  it  ? ’ 

“ ‘ Simply  by  good  oil,  wicks  properly  cut  and  trimmed,  lenses 
clean,  and  an  opaque  screen  faced  with  white  paper.’ 

“‘And  what  a beautiful  picture  that  is!’  said  he:  ‘America, 
isn’t  it  ? ’ 

“ ‘ Yes.’ 

“ ‘ Whose  slide  is  it  ? ’ 

“ ‘ Woodbury’s.’ 

“ ‘ It’s  very  nice,  but  I don’t  like  the  size 5 (3^  x 4*).  c I have 
bother  enough  with  slides  of  different  sizes  already,  and  I don’t 
care  to  introduce  another.’  • 

“ ‘ Well,’  I replied,  ‘ I think  the  Woodbury  slide  the  best  size, 
and  can  give  you  many  reasons  for  it.  One  is  that  you  have  only 
one  chance  of  getting  the  picture  the  wrong  way,  whereas  in  the 
square  slide  the  chances  are  three  to  one.  However,  let  us  go  on.’ 

“ My  second  picture  came  on  very  nicely. 

“ ‘ That’s  good,  too,’  said  my  friend.  ‘ Is  that  a Woodbury 
slide  ? ’ 

“ ‘ No,  it’s  York’s  ’ (3^  x 3^).  So  I varied  by  putting  in  a square 
slide,  then  a Woodbury,  changing  them  about  indiscriminately  for 
some  eight  or  nine  pictures,  when  my  friend  turned  round,  re- 
marking, 

“ ‘ How  beautifully  they  dissolve,  and  how  accurately  they 
register ! There  is  not  the  slightest  alteration  in  the  margin,  not- 
withstanding you  use  slides  of  different  sizes  every  time  ’ (which  I 
did  purposely).  ‘ How  do  you  manage  it  ? ’ 

“ ‘ By  means  of  my  carriers,  which  are  fixtures  in  the  lanterns, 
the  aperture  in  them  forming  the  margin  of  the  picture,  being 
slightly  less  than  the  paper  mount  inside  the  slide;  and  both 
carriers  being  exactly  alike,  the  pictures  are  simply  passed  through. 

8—2 


no 


THE  MAGIC  LAN  TEEN  MANUAL 


Also  on  the  carriers  I have  different  lengths,  or  stopping-edges, 
suitable  for  the  different  sizes  of  slides.’  (This  the  accompanying 
drawing  will  show). 

“My  friend  was  so  highly  pleased  with  the  carriers  that  he 
ordered  a pair  the  next  day.  I have  shown  them  to  many  lantern 
friends,  who  all  acknowledge  their  simplicity  and  efficiency.  I 
shall  be  glad  to  see  any  improvements  that  your  readers  may 
suggest.  It  will  be  seen  from  the  drawing  how  the  carrier  is 
applied.  In  placing  a picture  into  the  carrier  to  start  with,  it  needs 
no  fixed  stop ; the  second  picture,  according  to  its  size  and  that 
of  the  first  one,  must  be  pushed  to  one  or  other  of  the  stopping- 
edges,  by  which  means  the  first  picture  will  be  pushed  into  its  right 
position  in  the  centre  of  the  disc.  Thus,  suppose  the  first  picture 
to  be  si  x 3^,  and  the  second  to  be  3!  x si,  use  Stop  No.  2.  Now, 
suppose  the  first  picture  to  be  3iX'4|  (Woodbury  size),  and  the 
second  picture  the  same  size,  use  No.  1,  or,  as  I always  remember 
it,  the  longest  slide  and  the  longest  stop,  also  the  shortest  slide 
and  the  shortest  stop;  and  suppose  you  use  a Ferrier  size,  stop 
No.  4;  in  case  you  have  si  X si  iu  the  carrier,  and  the  next  picture 
is  si  x 4 i,  use  also  Stop  No.  4;  in  case  you  have  a Woodbury  slide 
in  the  carrier,  and  have  si  x 3^  following,  use  Stop  No.  3.  Although 
this  may  seem  a little  complicated  at  first  to  some  as  I have  ex- 
plained it,  I can  assure  you  in  practice  it  is  very  simple.  It  will 
be  seen  from  the  diagram  that  the  grooves  are  very  wide,  suitable 
for  the  thickest  slide,  and  by  having  two  little  springs  arranged  in 
the  grooves  at  the  top  and  bottom,  the  pictures  are  always  kept  in 
one  definite  position,  preventing  the  passage  of  one  slide  over  the 
other,  or  the  possibility  of  two  slides  getting  locked,  as  is  often  the 
case  with  thin  French  slides.  Another  advantage  is  that  after 
once  focussing,  readjustment  is- seldom,  if  ever,  required.” 

Although  this  is  the  best  form  of  “push  through”  Carrier,  and 


CARRIERS. 


Ill 


most  suitable  for  a single  lantern,  or  for  even  a small  Biunial 
Lantern,  it  has  a great  disadvantage,  when  using  it  with  a large 


Fig.  69. 

lantern,  by  requiring  both  hands  when  changing  slides — one  to 
push  in  the  new  slide  and  the  other  to  take  out  the  exhibited 


Fig.  71. 


slide  at  the  opposite  side  of  the  lantern.  This  drawback  is  over- 
come by  the  ingenious  Self-registering  Carrier  of  Mr.  Beard  shown 
at  Fig.  69. 


1 12 


THE  MAGIC  LANTERN  MANUAL. 


The  writer  has  had  a set  of  three  ol  these  carriers  in  use  with 
his  Triple  Lantern  for  some  time,  and  no  hesitation  in  saying 
that,  when  well  made,  they  are  the  best  carriers  for  automatically 
registering  slides  of  various  sizes  ever  used  with  the  lantern.  It 
matters  not,  whatever  be  the  length  of  slide,  from  3 inches  to  41- 
inches,  it  becomes  automatically  centred  on  being  placed  on  the 
brass  runner,  Fig.  70,  and  pushed  home.  Each  carrier  is  pro- 
vided with  two  metal  masks,  Fig.  71,  which  are  made  to  slide  in 
grooves  immediately  behind  the  photograph,  and  thus  ensures 
perfect  registration  at  the  margin  of  the  disc. 


SCARCELY  any  subject  of  photography  can  be  shown  on  the 
screen  to  excel  that  of  Statuary.  In  many  cases  these  are 
stopped  out  with  Indian-ink,  and  nothing  is  seen  but  the  simple 


lantern,  and  the  dissolving  conducted  very  slowly  until  the  statue 
appears  in  full,  with  the  shadow  portions  a deep  blue  in  comparison 


STATUARY. 


statue  upon  a black  ground  in  bold 
relief.  One  very  effective  way  to 
exhibit  this  class  of  slide  by  a dis- 
solving lantern  is  to  dissolve  them 
into  blue  glass.  This  is  done  as 
follows : First  place  a blue  glass  in 
one  lantern  (sheets  of  coloured  gela- 
tine will  answer  the  same  purpose, 
and  may  be  made  to  any  required 
depth  of  shade),  and  through  it  pro- 
ject a disc  on  to  the  screen.  A sta- 
tuary slide  is  now  placed  in  the  other 


STATUARY. 


1 13 

with  the  lighter  parts ; now  gently  dissolve  back  again,  leaving 
the  blue  disc ; change  the  picture,  and  proceed  as  before. 

Another  way  of  exhibiting  statuary  slides  is  by  means  of  two 
slide  tinters  (shown  at  Fig.  72).  These  consist  of  flanges  fitted 
to  the  front  parts  of  the  objectives,  on  which  are  fixed  metallic 
frames,  each  holding  a sheet  of  thin  coloured  gelatine  ; an  opaque 
shutter  is  also  attached  to  each,  for  application  when  it  is  neces- 
sary for  the  lanterns  to  remain  in  darkness.  The  method  of 
procedure  is  this  : Project  a picture  on  the  screen  through  the 
gelatine;  now  gently  raise  the  frame  holding  the  gelatine  until 
the  picture  has  increased  much  in  brightness ; then  gradually 
lower  the  frame.  With  the  second  lantern  a similar  operation  will 
be  performed ; so  that,  while  dissolving  one  picture  into  the  other, 
both  frames  will  be  down. 

The  slide  tinter  is  very  useful  for  a variety  of  effects,  such  as 
sunsets,  moonlights,  etc. ; also  for  giving  to  ordinary  photographs, 
in  many  cases,  the  effect  of  a coloured  slide,  by  the  judicious  ap- 
plication of  different  coloured  sheets  of  gelatine  for  sky  and  fore- 
ground. These  different  sheets  may  be  introduced  into  the  frame 
at  will. 

Superior  to  the  slide  tinters  fixed  upon  the  nozzles  of  the  objec- 
tives are  sheets  of  coloured  glass  inserted  between  the  light  and 
the  condenser,  by  means  of  apertures  cut  in  the  body  of  the 
lantern,  and  closed  when  not  in  use  by  polished  brass  doors. 

Another  novel  effect  when  exhibiting  statuary,  is  by  means  of 
the  roller  curtain  shutter,  described  at  page  121. 


114 


THE  MAGIC  LANTERN  MANUAL. 


COLOURING  OF  SLIDES. 

IN  the  Colouring  of  Slides  for  Magic  Lantern  purposes  the 
greatest  care  is  necessary,  and  considerable  practice  is  re- 
quired ere  anything  like  a favourable  result  can  be  achieved.  The 
best  light  by  which  to  operate  is  lamp  or  gaslight.  This  is  a benefit 
to  the  amateur,  whose  time  during  the  day  is  perhaps  fully  occu- 
pied with  matters  pertaining  to  jQ  s.  d.}  and  therefore  could  not 
devote  so  much  daytime  to  the  subject  as  would  insure  success. 

Colours  in  both  oil  and  water  are  used  to  obtain  the  best  results, 
where  richness,  depth,  brilliancy,  and  force  of  effect  are  desired. 

It  should  be  remembered 
that  none  but  transparent 
colours  must  be  used.  These 
can  be  purchased  from  most 
artists5  colourmen,  ready  ar- 
ranged in  boxes  with  all 
the  requisite  materials  for 
painting  on  glass,  such  as 
“ fixings,”  palette,  palette- 
knife,  leather  dabbers,  tur- 
pentine, mastic-varnish,  pale 
drying-oil,  and  gold  size,  etc. 
A large  number  of  brushes 
are  necessary — one  for  each 
kind  of  colour  used  in  oil 
or  water  of  the  different  tints.  The  next  thing  required  is  a 
suitable  desk  or  easel,  with  a glass  back,  as  shown  in  Fig.  73. 
The  slide  to  be  coloured  should  be  perfectly  clear  in  the  transpa- 
rent parts,  and  not  too  cold  in  tone.  It  should  not  be  over  printed, 


COLOURING  OF  SLIDES. 


IIS 


as  in  that  case  there  would  be  a want  of  vigour  and  contrast ; and 
as  the  colourist  can  strengthen  foregrounds  and  other  objects  of 
detail,  or  throw  back  those  wanting  in  relief  or  gradation,  a slightly 
under-exposed  print  is  to  be  preferred.  Still,  much  will  depend 
upon  the  nature  of  the  subject,  as,  for  instance,  where  a wide4 
gloomy,  and  desolate  effect  is  sought,  a slightly  over  printed  slide 
will  be  better ; and  where  a wide  expanse  of  country,  with  distant 
mountains,  is  desired,  a soft,  delicate  print  will  aid  the  artistic 
colourist  in  securing  air  and  light.  If  buildings  and  figures  are 
to  be  the  principle  objects,  the  print  should  be  correctly  exposed, 
as  if  to  be  shown  without  any  colour. 

We  commence  first  with  the  water-colour,  by  mixing  on  the 
palette  such  colours  as  Prussian  blue,  burnt  sienna,  crimson  lake, 
and  yellow  to  some  of  the  numerous  compounds,  ranging  through 
browns,  purples,  greens,  and  neutral  tints  to  a very  powerful  trans- 
parent black,  to  each  of  which  a little  ox-gall  should  be  added. 

Proceed  by  strengthening  the  masses  of  the  deeper  shadows,  the 
markings  and  cast  shadows  of  the  foreground,  etc.  A full  brush 
should  be  used,  and  the  colour  applied  in  an  even  wash.  The 
colour  should  not  be  too  strong,  or  the  edges  of  the  wash  will  be 
disagreeably  visible.  If,  however,  the  wash  is  too  strong,  apply 
the  action  of  the  breath,  and  whilst  still  moist,  go  over  it  with  a 
flat  camel’s-hair  brush.  No  attempt  must  be  made  to  apply  a 
second  colour  until  the  first  is  quite  dry.  Should  the  part  require 
strengthening,  another  light  wash  may  be  applied,  and  thus  any 
depth  of  colour  may  be  obtained.  Foreground  objects  should  be 
made  to  stand  forward  more  prominently,  and  the  masses  of  foliage 
made  distinctly  visible. 

Before  applying  what  are  called  local  colours,  it  is  well  to  apply 
a very  thin  coat  of  transparent  enamel  varnish  over  those  already 
applied.  When  this  is  dry  the  local  colouring  can  be  pro- 


ii  6 


THE  MAGIC  LANTERN  MANUAL. 


ceeded  with,  and  may  be  carried  over  all  the  parts  except  the  high 
lights  and  sky,  which  are  reserved  for  oil  or  varnish  colours 
specially  prepared  for  the  purpose,  as  previously  stated.  These 
(to  be  effective)  require  more  skill  in  using  than  water-colours. 
The  brushes  are  similar  to  those  used  with  the  water-colours,  with 
the  addition  of  a few  hog’s-hair  tools  and  a dabber,  made  from  an 
old  white  kid  glove,  by  stuffing  a piece  of  the  kid  with  cotton- 
wool. In  proceeding  with  the  sky  the  hog’s-hair  brush  is  used, 
held  perpendicular,  and  the  colour  dabbed  or  stippled  on,  after 
which  a broad  camel’s-hair  brush  is  swept  over  the  surface  to 
make  the  colours  smooth.  The  dabber  is  next  used  to  make  it 
still  more  even.  For  the  smaller  surfaces,  such  as  the  high  lights 
in  distant  mountains,  &c.,  a sable  brush  may  be  used  with  advan- 
tage. These  colours  may  be  thinned  with  a little  turpentine  and 
a small  portion  of  dryers  and  gold  size  added. 

To  facilitate  the  drying,  heat  may  be  applied,  which  is  best 
done  upon  a small  iron  plate  under  which  a gaslight  or  small 
Brunsen’s  burner  is  fixed.  The  greatest  care  must  be  taken  to 
avoid  dust,  and  no  brush  used  for  two  colours  without  previously 
cleansing. 

The  principles  of  art,  which  guide  the  painter  on  canvas  or 
paper,  apply  equally  to  transparency  colouring.  The  highest  light, 
deepest  shadow,  and  brightest  colours  occur  in  the  foreground ; 
in  the  middle  distance  the  colours  lose  their  force,  and  in  the 
extreme  distance  the  colours  should  be  used  still  less  forcibly  or 
in  lighter  tints,  remembering  that  blue  is  the  coldest  colour  and 
the  most  retiring,  and  therefore  should  predominate  in  the  distant 
parts  of  the  landscape.  Red  is  warmer  in  colour,  and  is  more 
used  in  combination  for  the  nearer  compositions,  and  adds  con- 
siderable force  in  foregrounds,  buildings,  figures,  &c.  Orange 
and  yellows  may  be  used  with  discretion  in  nearer  objects  and 


COLOURING  OF  SLIDES. 


II 7 

foregrounds.  Yellow,  being  the  lightest  of  colours,  should  occur 
in  the  brightest  parts  of  the  picture. 

Daylight  effects  should  be  kept  warm  in  tone;  moonlights, 
cold. 


Before  attempting  to  colour  photograph  transparencies,  the 
amateur  should  practice  upon  a few  of  the  outlines  printed  upon 
glass,  as  at  Fig.  74.  These  are  sold  by  many  of  the  artists’ 
colourmen  and  lantern  slide  dealers. 


Xl8  THE  MAGIC  LA  A7  TEEIV  MAN  HAL. 


EFFECT  SLIDES. 

IN  using  Effect  Slides,  two  or  more  lanterns  are  necessary, 
These  slides  are  usually  hand  painted,  although,  of  late, 
photography  has  been  turned  to  good  account  in  this  direction, 
and,  notwithstanding  the  extra  care  and  trouble  in  their  prepara- 
tion, they  amply  repay  for  this  expenditure. 


/'4>.  75.  Fig.  76. 


Some  very  wonderful  effects  can  be  produced  : among  these  are 
the  change  from  day  to  night,  summer  to  winter,  the  formation  of 
rainbows,  tempests  at  sea,  with  shipwrecks  and  lightning,  the 
storming  of  forts,  etc. 

To  more  clearly  illustrate  the  object  of  effect  slides,  let  us  de- 
scribe an  exhibition  of  a set  of  slides  called  the  “ Orphan’s  Dream.” 
This  set  consists  of  two  slides  (Figs.  75  and  76).  In  one  lantern  is 
placed  the  foundation  slide  (Fig.  75),  representing  a child  asleep 
upon  a couch,  and  in  the  other  lantern  is  placed  the  effect  slide 


EFFECT  SLIDES. 


1 19 

(Fig.  76).  First  the  foundation  slide  is  displayed ; and  then,  on 
commencing  the  dissolving,  the  effect  will  be  made  to  appear  gra- 
dually and  then  disappear. 

Messrs.  F.  York  and  Son  have  produced  many  beautifully- 
arranged  effect  slides,  illustrating  some  of  the  works  of  the  late 
Charles  Dickens — “Gabriel  Grub,”  “The  Christmas  Carol/’  also 
“The  Pilgrim’s  Progress,”  “How  Jane  Conquest  Rang  the  Bell,” 
and  many  others — all  from  life  models. 

In  cases  where  several  effects  follow  alternately,  two  lanterns 
may  be  used,  by  placing  the  foundation  picture  in  one,  and  dis- 
solving the  effects  alternately  in  the  other  lantern ; but  by  far  the 
best  plan  is  to  use  three  lanterns,  and  by  this  means  the  dissolv- 
ing is  made  perfect.  Thus,  in  the  slides  of  the  “ Soldier’s  Dream,” 
the  principal  or  foundation  slide  represents  a soldier  fallen  asleep 
on  the  battle-field,  beside  the  camp  fire.  He  is  supposed  to  be 
dreaming,  and  the  vision  of  a happy  home  is  caused  to  appear 
in  the  smoke  of  the  camp  fire  by  means  of  a second  lantern; 
now  this  vision  is  changed  to  one  of  departure  for  war,  and  fol- 
lowed by  engagements  on  the  battle-field,  and  victory  in  the  end. 
It  will  be  seen  that  the  foundation  slide  must  remain  on  the  screen 
the  whole  time,  and  will  therefore  occupy  one  lantern.  The  first 
effect  slide  must  be  placed  in  the  second  lantern,  and  made  to 
appear ; the  second  effect  slide  must  be  placed  in  the  third  lan- 
tern, and  by  these  two  latter  lanterns  the  effects  may  be  dissolved 
without  interfering  with  the  foundation  slide. 

In  some  effects  even  more  than  three  lanterns  are  required,  and 
at  the  Royal  Polytechnic  Institution  as  many  as  six  lanterns  have 
been  in  use  at  one  time  for  the  production  of  effects,  such  as  the 
Siege  of  Delhi,  in  which  the  fire  of  artillery,  the  bursting  of  shells, 
etc.,  are  portrayed.  Four  lanterns  were  most  frequently  used  at  the 
above  institution.  An  illustration  (Fig.  77)  shows  before  and 


THE  MAGIC  LANTERN  MANUAL, 


MECHANICAL  SLIDES. 


121 


behind  the  scenes  at  the  same  institution  during  a lantern  exhibi- 
tion of  the  above  description,  and  is  taken  from  Professor  Pepper’s 
“ Play-book  of  Science,”  by  permission  of  the  publishers.* 

“ The  optical  effects  were  assisted  by  various  sounds  in  imita- 
tion of  war’s  alarms,  for  the  production  of  which  more  volunteers 
than  were  absolutely  required  would  occasionally  trespass  behind 
the  scenes,  and  produce  those  terrific  sounds  that  some  persons 
of  a nervous  temperament  said  were  really  stunning.” 


HE  above  embrace  a variety  of  scientific  as  well  as  comic 


slides,  and  no  class  of  picture  can  be  made  more  entertain- 
ing or  instructive  than  a really  good  set  of  Astronomical  Slides. 
Among  this  class  comes  the  Roller  Curtain  Slide  and  Shutter . 
This  is  one  of  the  most  novel  additions  to  modern  lanterns,  and 
no  first-class  instrument  is  made  without  it.  The  effect  is  gene- 
rally produced  at  the  opening  of  an  exhibition,  when  the  first  slide, 
a curtain  (either  hand  painted  or  photographic),  arranged  to  imi- 
tate a theatrical  drop  scene,  with  all  the  necessary  tassels,  cords, 
valences,  etc.,  occasionally  an  appropriate  inscription  or  a device, 
forming  a centrepiece. 

This  curtain  is  to  be  rolled  up,  displaying  the  view  as  if  it  were 
under  the  curtain,  and  by  its  use  statuary  slides  are  shown  in  a 
very  pleasing  manner.  The  shutter  used  in  connection  with  the 
curtain  slide  consists  of  a stout  sheet  of  brass,  exactly  the  length 
from  centre  to  centre  of  the  optical  systems,  placed  between  the 
condensers  and  the  slide  when  in  position,  and  so  arranged  that 


MECHANICAL  SLIDES. 


See  also  Professor  Pepper’s  more  advanced  work,  “ Cyclopaedic  Science 
Simplified,” 


122 


THE  MAGIC  LANTERN  MANUAL. 


by  side  pieces  sliding  in  grooves  it  may  be  drawn  up  from  the  top, 
as  shown  in  position  in  Fig.  55.  To  use  it  in  a Biunial  Lantern 
the  curtain  slide  must  be  placed  in  the  bottom  lantern,  and  as  the 
shutter  is  raised  the  uncovering  of  the  slide  has  the  appearance  of 
rolling  the  curtain  down  on  the  sheet.  The  view  to  be  shown,  or 
the  statuary,  is  introduced  in  the  top  lantern,  and  the  light  turned 
on  to  both.  The  shutter  covering  the  top  slide,  no  light  is  allowed 
to  pass  until  the  shutter  is  pushed  down,  which,  if  of  the  correct 
length,  will  cover  the  lower  portion  of  the  curtain,  and  uncover  the 
lower  part  of  the  view  at  the  same  time.  If  statuary  be  shown 
this  way,  the  curtain  should  be  lowered  again,  another  slide  sub- 
stituted, and  proceeded  with  as  before. 

With  a triple  lantern  a pair  of  side  curtains,  thrown  on  with  the 
bottom  lantern,  and  kept  there  all  the  time  statuary  is  being  ex- 
hibited, still  further  increases  the  effect,  and  is  very  beautiful.  In 
this  case  the  centre  curtain  is  masked  to  fit  inside  the  side 
curtains. 

The  same  apparatus  may  be  used  occasionally  to  advantage, 
instead  of  dissolving ; and  if,  in  course  of  a lecture,  a map  is  to  be 
shown,  it  should  be  rolled  down  and  up  again,  as  the  curtain  was. 

A beautiful  mechanical  effect  is  produced  by  the  rackwork  slide, 
the  Chromatrope  (Fig.  79).  This  was  invented  by  Mr.  Childe, 
the  inventor  of  dissolving  views.  It  consists  of  two  discs  of  glass 
painted  in  brilliant  transparent  colours,  generally  radiating  from 
the  centre  to  the  outside,  and  forming,  when  placed  face  to  face, 
the  reverse  of  each  other.  The  handle  on  being  turned  gives  a 
rotary  motion  to  the  glass  discs  in  opposite  directions.  The  result 
is  an  ever-varied  change  of  design  and  colour. 

A great  variety  of  designs  can  be  adapted  to  the  same  mechanical 
arrangement  for  displaying  geometrical  and  chromatic  effects.  Two 
pieces  of  perforated  zinc  introduced  give  some  very  extraordinary 


MECHANICAL  SLIDES. 


123 


Fig.  78. 


Fig.  79. 


Fig.  80. 


Fig:  82. 


Fig.  81. 


Fig.  83. 


Fig  85. 


Fig.  84. 


9 


124 


THE  MAGIC  LANTERN  MANUAL. 


geometrical  effects,  also  two  pieces  of  wire  gauze  give  a variety  of 
designs  of  the  watered  silk  type. 

The  Windmill  (Fig.  78)  is  another  rackwork  slide.  In  this  case 
only  one  disc  is  caused  to  revolve,  that  one  on  which  the  sails  of 
the  mill  only  are  painted,  the  landscape  being  painted  on  a fixed 
disc.  Similar  to  this  is  a slide  of  a mill  with  the  water-wheel  in 
motion,  also  a slide  representing  a man  swallowing  rats. 

Transformation  Comic  Slides  are  made  in  an  endless  variety 
of  subjects.  The  one  illustrated  at  Figs.  80  and  81  represents  a 
wicked  monkey,  who,  having  caught  a cat,  persists  in  dipping 
pussy  over  head  in  the  water-tub. 

Lever  Slides  (Figs.  82  and  83)  are  made  of  two  discs,  one  of 
which  only  is  made  movable.  Thus,  for  instance,  one  representing 
a cow  having  come  down  to  the  water  to  drink,  has  the  body  only 
Of  the  cow  painted  on  one  disc,  while  the  head  and  neck  are  painted 
on  the  movable  disc.  On  the  movement  of  the  lever  the  cow  is 
represented  very  naturally  as  taking  a drink. 

Conundrum  Comic  Slides  are  similar  in  construction  to  trans- 
formation comic  slides.  The  frame  simply  carries  an  opaque  plate, 
in  the  centre  of  which  an  aperture  is  cut,  and  on  the  loose  sliding 
glass  is  printed  a conundrum,  and  adjoining  it  the  answer.  The 
conundrum  being  first  shown,  the  answer  is  seen  by  pulling  out  the 
slide.  Figs.  84  and  85  represent  the  positions  during  question  and 
answer. 

One  of  the  best  mechanical  comic  slides  ever  invented  is  Beale?s 
Choreutoscope.  It  consists  of  a frame  containing  one  long  slide, 
on  which  is  painted  a skeleton  in  six  different  positions.  In  the 
frame  is  an  aperture,  so  that  one  only  of  the  positions  can  be  seen 
at  a time.  A handle  is  so  arranged  at  the  back  that  by  turning 
the  same,  each  position  of  the  skeleton  is  made  to  appear  alter- 
nately, and  by  a very  ingenious  cam  motion  the  transit  from  one 


VIEWING  PICTURES. 


125 


position  to  another  is  performed  instantaneously ; also  a shutter  is 
caused  to  close  the  aperture  entirely  at  the  time  of  transit,  thereby 
preventing  the  possibility  of  any  one  seeing  any  portion  of  two 
positions  at  once.  The  effect  produced  on  working  the  handle  is 
that  of  a skeleton  performing  an  extempore  step  dance. 

In  addition  to  the  mechanical  comic  slides,  a variety  of  humorous 
ones  are  now  produced,  for  exhibiting  in  the  ordinary  way  nursery 
tales,  FEsop’s  “Fables,”  and  comic  stories,  as  “The  Tale  of  a Tub,” 
“The  Fox  and  the  Stork,”  “The  Elephant’s  Revenge,”  etc.,  all 
conducive  to  the  greatest  merriment.  Motto  Slides,  such  as  “Wel- 
come,” “Adieu,”  “Good  night,”  etc.,  if  judiciously  used,  give  eclat 
to  an  entertainment. 

Chromo  Pictures.— -Messrs.  J.  Barnard  & Son,  have  published 
a variety  of  the  above  for  use  in  the  Magic  Lantern.  The  subjects 
consist  chiefly  of  Scriptural  stories,  “-Dsop’s  Fables,”  natural 
phenomena,  dissolving  view  effects,  and  a long  list  of  comic  slides. 
These  pictures  are  printed  upon  paper  in  highly  brilliant  and  trans- 
parent colours.  By  using  the  materials  supplied,  and  keeping  to 
the  instructions  given,  the  amateur  may  soon  increase  his  stock  of 
slides,  at  a small  cost  and  a little  trouble. 

VIEWING  PICTURES. 

Having  now  considered  the  different  forms  of  lanterns,  with 
their  details  and  appliances,  as  well  as  the  various  classes  of  pic- 
tures, it  may  be  as  well' to  say  a few  words  as  to  the  most  effective 
way  of  viewing  a lantern  exhibition.  It  must  be  admitted  that 
however  fine  a picture  or  a photograph  may  be  when  viewed  in 
the  hand,  upon  being  magnified  on  the  screen  some  two  or  three 
thousand  times,  its  defects  will  be  manifest  by  a near  observer,  and 
it  is  well  known  that  many  very  beautiful  pictures  viewed  from 
a distance  assume  a flat,  coarse,  and  dauby  appearance  upon  closer 

9—2 


126 


THE  MAGIC  LANTERN  MANUAL. 


inspection.  Now,  by  uniting  these  facts,  we  arrive  at  the  proper 
position  for  viewing : the  nearer  we  are  to  the  screen,  the  coarser 
and  flatter  will  the  picture  be  seen,  and  as  we  recede,  its  defects 
become  less  apparent ; but  were  we  to  recede  too  far,  not  only 
would  the  defects  disappear,  but  also  the  details,  so  that  under 
these  circumstances  the  best  position  for  viewing  is  close  to  the 
lantern. 

Some  attempts  have  been  made  to  show  pictures  on  the  screen 
in  relief,  similar  to  stereoscopic  representations,  and  some  experi- 
mentalists have  actually  asserted  their  success  in  combining  bino- 
cular pictures  bv  means  of  two  lanterns.  A very  little  study  of 
binocular  vision,  or  of  the  stereoscope,  will  convince  any  one  that 
such  an  effect  is  impossible  to  produce. 

From  the  introduction  in  Sir  David  Brewster’s  work  on  the 
stereoscope,  published  by  Mr.  John  Murray,  the  following  is  ex- 
tracted : — “When  the  artist  represents  living  objects,  or  groups  of 
them,  and  delineates  buildings  or  landscapes,  or  when  he  copies  from 
statues  or  models,  he  produces  apparent  solidity,  and  difference  of 
distance  from  the  eye,  by  light  and  shade,  by  the  diminished  size- 
of  known  objects  as  regulated  by  the  principles  of  geometrical 
perspective,  and  by  the  variation  in  distinctness  and  colour  which 
constitute  what  have  been  called  aerial  perspective ; but  when  all 
the  appliances  have  been  used  in  the  most  skilful  manner,  and  art 
has  exhausted  its  powers,  we  seldom,  if  ever,  mistake  the  plain 
picture  for  the  solid  which  it  represents.  The  two  eyes  scan  its 
surface,  and  by  their  distance-giving  power  indicate  to  the  observer 
that  every  point  of  the  picture  is  nearly  at  the  same  distance  from 
his  eye.  But  if  the  observer  closes  one  eye,  and  thus  deprives  him- 
self of  the  power  of  determining  differences  of  distance  by  the  con- 
vergency  of  the  optical  axes,  the  relief  of  the  picture  is  increased. 
When  the  pictures  are  truthful  photographs,  in  which  the  variations 


DESCRIPTIVE  LECTURES . 


127 


of  light  and  shade  are  perfectly  represented,  a very  considerable 
degree  of  relief  and  solidity  is  thus  obtained,  and  when  we  have 
practised  for  a while  this  species  of  monocular  vision,  the  drawing, 
whether  it  be  a statue,  a living  figure,  or  a building,  will  appear  to 
rise  in  its  different  parts  from  the  canvas.” 

And  at  page  46  of  the  same  work  : — “ When  we  view  a picture 
with  both  eyes,  we  discover,  from  the  convergence  of  the  optic 
axes,  that  the  picture  is  on  a plain  surface,  every  part  of  which  is 
nearly  equidistant  from  us.  But  when  we  shut  one  eye,  we  do  not 
make  this  discovery,  and  therefore  the  effect  with  which  the  artist 
gives  relief  to  the  painting  exercises  its  whole  effect  in  deceiving 
us,  and  hence  in  monocular  vision  the  ‘ relievo  ’ of  the  painting  is 
much  more  complete.” 

As  this  applies  equally  to  the  picture  on  the  screen,  it  is  clearly 
shown  that  with  one  eye  the  best  effect  is  obtained,  and  the  nearer 
the  observer  is  to  the  screen,  the  more  important  this  becomes. 


HEN  slides  can  be  shown  in  series,  lectures  or  descriptions 


of  the  views  should  be  given,  not  necessarily  a formal  lec- 


ture, as  from  the  amateur  they  are  more  effective  when  spoken  than 
read.  Set  lectures  are  to  be  purchased,  at  small  cost,  on  very  many 
subjects,  or  can  be  arranged  from  tourists’  guide  books,  which  can 
be  got  of  the  whole  world.  After  all  the  slides  are  arranged  and 
numbered  in  boxes  in  the  order  to  be  shown,  each  slide  should  be 
taken  out  separately,  and  the  lecturer  should  now  rehearse  several 
times  in  private  his  description,  with  the  slides  before  him,  and  if 
needs  be,  pointing  out  the  places  of  interest,  as  he  will  when  the  pic- 
ture is  on  the  screen.  Even  when  slides  are  not  in  complete  series, 


DESCRIPTIVE  LECTURES. 


128 


THE  MAGIC  LANTERN  MANUAL. 


and  the  exhibitor  has  to  make  up  his  entertainment  by  slides  of 
various  places,  one  or  two  of  London,  a few  of  Paris,  Switzerland, 
Egypt,  etc,  a description  of  the  views  should  in  all  cases  be  given, 
for  instead  of  simply  calling  out  “ the  Pyramids  of  Egypt,”  if  some- 
thing can  be  said  of  their  age,  by  whom  built,  and  for  what  their 
supposed  purpose,  their  size,  position,  etc.,  a double  interest  is 
given  to  the  picture.  It  is  as  well  in  giving  a 
mixed  entertainment,  or  “ Scenes  in  Many 
Lands,”  to  keep  those  belonging  to  one 
country  together,  also  those  of  another,  and 
let  the  whole  be  exhibited  in  something  like 
order,  as  nothing  looks  more  disorderly  than 
first  to  be  shown  a picture  in  America,  then 
one  of  Paris,  next  one  of  Niagara  Falls,  etc. 
A little  music  will  add  much  to  the  charm 
of  an  exhibition,  care  being  taken  that  the 
airs  selected  should  be  in  keeping  with  the 
subjects  shown.  National  airs  may  be  intro- 
duced in  their  proper  places  with  effect,  but 
nothing  would  appear  so  ridiculous  as  to 
hear  the  tune  of  “Johnny  comes  marching 
home  again,”  to  a picture  of  “ the  Return  of 
the  Prodigal  Son  ” on  the  screen. 


READING  DESK. 

A MOST  useful  and  portable  combined 
Lamp  and  Reading-Desk  is  shown  in 
Fig.  86,  fitted  up  for  use. 

The  Lamp  is  similar  to  the  ordinary  railway  travellers’  carriage 


READING  DESK . 


129 


reading-lamp,  in  which  standard  size  candles  are  used,  and  which 
are  fitted  into  a spring  socket,  so  that  the  flame  is  always  kept  at 
the  same  level.  This  lamp  a is  fixed  on  the  top  of  a rod  c c, 
which  for  the  convenience  of  packing  is  made  in  two  lengths, 
coupled  in  the  centre  by  a ferrule.  The  lower  end  of  the  rod 
is  fixed  in  a brass  socket  d,  which  forms  a foot;  underneath 
this  is  a short  strong  taper  screw,  by  which  the  whole  is  fixed  to 
the  floor. 

The  desk  is  composed  of  two  thin  pieces  of  wood  hinged 
together,  as  shown,  and  is  attached  to  the  stand  by  means  of  a 

hook  and  socket  just  below  the 
lamp,  which  is  also  provided  with 
a silvered  reflector  and  an  adjust- 
ing flap,  answering  the  double  pur- 
pose of  throwing  the  light  on  to 
the  desk  whilst  preventing  the 
light  from  escaping  into  the  room. 

Another  Reading  Lamp  is  shown 
at  Fig.  87,  which  in  many  respects 
is  superior  to  that  previously 
described.  It  is  arranged  to 
burn  sperm  oil,  and  a screw  cap 
serves  as  an  extinguisher,  and 
prevents  the  oil  from  running  out  when  being  carried.  It  is  pro- 
vided with  a silent  signal  at  s,  and  a bell  at  b if  necessary  ; there 
is  also  a match-box  fitted  at  m,  the  whole  packing  into  a box 
3x3x9^  inches. 


Fig.  87. 


130 


THE  MAGIC  LANTERN  MANUAL. 


SCIENTIFIC  PROJECTIONS. 

IT  seems  very  surprising  that  the  attention  of  science  teachers 
has  not  been  more  given  to  the  Magic  Lantern,  although 
latterly  many  are  becoming  alive  to  the  importance  of  its  appli- 
cation, for  not  only  can  an  effect  be  more  clearly  shown  to  a large 
assembly,  but  less  bulky  and  less  expensive  apparatus  are  needed. 
Moreover,  only  one  subject  being  treated  at  a time,  the  attention 
of  the  student  can  be  more  closely  concentrated  on  the  one  point. 
It  is  to  be  hoped  that  more  consideration  may  be  given  to  this 
instrument  as  a medium  for  scientific  education,  and  as  appliances 
and  apparatus  are  becoming  more  general,  we  may  look  forward 
to  the  time  when  almost  every  branch  of  science  may  be  illustrated 
by  projection,  with  equal  facility  and  better  effect  than  can  be 
produced  at  the  lecturer's  table. 

DIAGRAMS, 

or  Drawings  for  the  illustration  of  lectures,  may  be  made  as 
follows : — 

A piece  of  glass  of  usual  size  for  lantern  slides  is  rubbed  with 
tallow,  or  waxed,  then  held  over  the  flame  of  a piece  of  burning 
camphor  : this  will  give  it  a perfectly  opaque  surface,  upon  which 
Diagrams  may  be  drawn,  or  it  may  be  written  upon  with  a fine 
point.  These,  when  projected  upon  the  screen  in  the  usual  way, 
have  the  appearance  of  chalk  drawings  upon  a black  ground. 
These  may  be  protected  by  another  glass,  and  made  up  as  ah 
ordinary  slide.  For  copying  drawings  or  diagrams  Mr.  Woodbury 
says:  aAn  excellent  medium  is  formed  by  making  a varnish  of 
gum  dammar  in  benzole  of  the  ordinary  consistency,  and  adding  a 
few  drops  of  india-rubber  to  the  same  solution.  This  dries  per- 


SCIENTIFIC  PROJECTIONS. 


131 

fectly  transparent,  and  allows  of  the  finest  writing  to  be  made 
upon  it  by  means  of  a steel  pen  and  Indian-ink.  When  circles 
are  required,  the  centres  may  be  obtained  for  the  compasses  by 
damping  a piece  of  card  and  attaching  it,  removing  same  when 
done  with.  By  coating  mica  with  this,  all  sorts  of  designs  may  be 
quickly  traced  from  any  scientific  work.” 

For  a Demonstrative  Lantern  few  are  more  suitable  than  the 
“ Sciopticon,”  which  may  be  used  with  its  powerful  oil-burning 
lamp  for  small  results,  or  also  with  the  lime-light  if  necessary. 

The  slide  stage,  a portion  of  which  is  removable,  is  most 
conveniently  arranged  for  the  adaptation  of  most  kinds  of  philo- 
sophical appliances;  the  objectives  are  easily  removed ; and  the 
condensers  are  arranged  from  the  outside , thus  offering  greater 
facilities  than  the  old  style  of  lantern  with  the  condensers  inside. 

OPTICAL  EXPERIMENTS 

may  be  exhibited : parallel,  converging,  and  diverging  rays  may  be 
shown  by  the  condensers,  and  intensity  of  illumination,  refraction, 
and  a variety  of  optical  phenomena  are  all  within  its  reach. 

THE  MICROSCOPE 

is  a valuable  attachment  to  the  Magic  Lantern.  The  lenses  in- 
troduced are  of  much  shorter  focus  than  the  ordinary  lantern 
objectives,  and  the  object  must  be  a greater  distance  from  the* 
condenser. 

The  best  position  is  shown  at  Fig.  88,  c being  the  condenser,  s 
the  slide,  and  o the  objective.  The  rays  emanating  from  the 
condenser  will  cross  at  the  focus,  and  then  diverge,  the  objective 
being  so  placed  that  all,  or  as  much  light  as  possible,  may  pass 
through  it.  The  light  may  be  drawn  back  so  as  to  obtain  the 
best  result.  It  is  most  important  in  using  this  adaptation  that  all 
the  parts  be  central. 


132 


THE  MAGIC  CANTEEN  MANUAL. 


When  objects  are  to  be  shown  a large  size,  enlarged  photo- 
graphs are  often  used;  but  these  are  never  so  good  as  originals, 
being  devoid  of  their  natural  colours.  As  most  microscopic  slides 
are  mounted  with  Canada  balsam,  they  must  not  be  kept  too  long 
in  the  lantern,  or  they  may  be  seriously  injured  by  the  heat  con- 
centrated upon  them.  To  avoid  this  danger,  the  best  lantern 
microscropes  are  provided  with  alum  tanks,  through  which  the 


Fig.  88. 


light  passes  previous  to  reaching  the  slide,  the  object  of  which  is 
to  absorb  the  heat  rays.  The  extent  of  magnifying  power  which 
may  be  employed  is  limited  by  the  amount  of  light  obtained  in 
illuminating  the  object,  so  very  high  powers  or  large  discs  should 
not  be  attempted  with  anything  less  than  the  lime  or  electric  light. 

Recently  the  Lantern  Microscope  has  received  much  considera- 
tion from  Mr.  Lewis  Wright,  assisted  in  the  mechanical  arrange- 
ments by  Mr.  H.  C.  Newton,  and  by  their  combined  efforts  a very 
perfect  instrument  has  been  produced,  as  shown  at  Fig.  89. 

"With  this  instrument  screen  demonstrations  can  be  given  by  the 


SCIENTIFIC  PROJECTIONS . 


133 


oxy-hydrogen  lime-light,  of  a character  hitherto  quite  unattainable. 
Ample  light  is  obtained  for  the  magnification  of  ordinarily  trans- 
parent subjects  to  1,250  diameters,  which  will  display  in  a clear 
and  beautiful  manner  all  the  parts  of  insects,  the  minute  details 
of  anatomical  sections,  vegetable  tissue,  &c.  A flea  may  be 
shown  upon  the  screen,  fifteen  feet  long,  quite  as  sharply,  and 
almost  as  brilliantly,  as  a magic  lantern  slide ; the  proboscis  of  a 


Fig.  89. 


blow-fly  is  easily  displayed  with  the  various  powers  from  eight  to 
fourteen  feet  long ; and  all  the  details  of  an  insect’s  eye  are  shown 
in  section  clearly.  The  circulation  of  the  blood  is  easily  displayed 
in  the  veins  of  the  living  frog,  and  pond  life  is  of  course  shown 
without  any  difficulty.  Where  transparency  of  ground  is  combined 
with  opacity  of  detail,  as  in  the  cornea  of  a fly’s  eye,  a magnifica- 
tion of  2,500  diameters  is  obtainable.  Geological  sections  are 
admirably  shown  either  by  ordinary  or  polarized  light. 


134 


THE  MAGIC  LANTERN  MANUAL. 


The  microscope  can  be  fitted  to  any  good  optical  lantern.  In 
the  special  lantern  constructed  for  use  with  the  instrument,  a triple 
5 -in.  primary  condenser  is  used,  similar  to  that  shown  at  Fig.  4, 
which  takes  up  the  large  angle  of  950  of  light  from  the  radiant. 
Almost  equal  results  can,  however,  be  obtained  with  the  4-in.  con- 
densers usually  supplied  in  optical  lanterns,  by  the  addition  of  a 
third  lens;  the  triple  5-in.  condenser  being  reckoned  to  give  15 
per  cent,  more  illumination. 

During  the  Franco-Prussian  War,  when  Paris  was  in  a state  of 
siege,  and  communication  with  the  outer  world  deemed  an  impos- 
sibility, despatches  and  copies  of  newspapers  were,  by  means  of 
micro-photographs  upon  thin  films  of  collodion,  carried  by  pigeons 
to  the  interior  of  the  capital.  These  films,  which  were  about 
2 inches  long  by  1 inch  wide,  contained  each  copies  of  sixteen 
pages  of  despatches,  each  page  consisting  of  5,ooq  letters,  the 
reduction  being  the  eight-hundredth  part  of  the  size  of  the  origi- 
nal. Twenty  of  these  despatches  could  be  carried  in  a quill 
attached  to  the  tails  of  these  novel  postmen.  As  soon  as  the 
despatches  were  received  at  the  telegraph  office,  they  were  placed 
between  two  plates  of  glass  and  inserted  in  the  microscope  lantern, 
the  electric  light  being  employed,  and  the  characters  were  repro- 
duced of  sufficient  size  to  be  read  and  copied  with  ease.  An 
illustration  of  this  forms  our  Frontispiece. 

Objects  suitable  to  the  lantern  microscope  are  whole  insects, 
butterflies,  wood  sections,  and  fine  crystals  of  many  chemicals, 
such  as  sulphate  of  copper,  sulphate  of  iron,  chloride  of  ammo- 
nium, chloride  of  barium,  alum,  camphor  dissolved  in  water,  etc. 
A variety  of  tank  experiments  also  may  be  introduced,  as  the 
ammalculae  in  water,  suitable  water  for  examination  being  found 
in  stagnant  pools,  or  water  in  which  flowers  or  hay  have  been 
standing  for  some  few  days.  A very  pretty  effect  may  be  wit- 


SCIENTIFIC  PROJECTIONS. 


135 


nessed  of  the  formation  of  crystals  if  a slip  of  glass  be  wetted 
with  a strong  solution  of  Epsom  salts,  and  then  placed  in  the 
microscope.  In  a short  time  the  water  will  evaporate  from  the 
upper  edge,  and  crystallization  will  at  once  begin ; if  too  slowly, 
it  may  be  hastened  by  blowing  upon  the  surface  of  the  slip ; very 
soon  the  screen  will  be  covered  with  a representation  of  a beauti- 
ful crystalline  formation.  A most  convenient  screen  for  exhibiting 
microscopic  objects  may  be  made  by  tracing-paper,  stretched  on  a 
youth’s  wooden  hoop,  as  described  at  page  87. 

THE  OXY-HYDROGEN  POLARISCOPE. 

This  is  an  instrument  with  which  one  of  the  most  interesting 
branches  of  science  can  be  studied.  To  attempt  an  explanation 
of  the  remarkable  phenomena  of  polarized  light  is  entirely  out  of 
the  limits  of  this  treatise,  therefore  we  will  content  ourselves  with 
a description  and  method  of  applying  the  instrument.  The  pecu- 
liar properties  called  polarization  may  be  imparted  to  light  in 
various  methods  of  refraction  and  reflection. 

It  is  about  forty  years  ago  that  Mr.  J.  F.  Goddard  received  the 
silver  medal  of  the  Society  of  Arts  for  his  invention  of  the  “Oxy- 
hydrogen  Polariscope,”  illustrated  at  Fig."  90.  Thus  described  : — 

“ In  this  instrument  a represents  the  oxy-hydrogen  blow-pipe,  b 
the  lime-cylinder,  and  diverging  rays  of  light  refracted  by  the  con 
densing  lens  c c c,  and  falling  upon  a mirror  b b,  consisting  of 
plates  of  flattened  crown  glass  placed  in  the  elbow  of  a tube,  bent 
to  the  polarizing  angle  of  crown  glass ; d,  converging  rays  of  polar- 
ized light  reflected  from  the  mirror ; h h,  a bundle  of  sixteen  plates 
of  mica  for  analysing  the  light  previously  polarized  by  reflection ; e, 
a double-reflecting  crystal  (film  of  selenite),  placed  in  focus  of  the 
object  glass  (1),  which  forms  an  image  of  the  crystal  upon  a disc 
or  screen  at  r.  As  the  analysing  bundle  of  mica  is  caused  to 


136 


THE  MAGIC  LANTERN  MANUAL. 


revolve,  the  image  of  the  selenite  upon  the  disc  undergoes  all  the 
change,  and  exhibits  alternately  the  primary  and  complementary 


SCIENTIFIC  PROJECTIONS. 


1 37 


colours  at  the  same  time,  one  being  reflected  in  the  direction  s, 
and  the  other  transmitted  and  seen  at  r.  The  great  advantage  of 
polarizing  the  light  from  a number  of  plates  is,  that  a beam  of  any 
required  dimension  can  be  obtained,  also  of  much  greater  intensity 
than  by  any  other  means ; for  whatever  single  surface  may  be  em- 
ployed, that  polarized  light  at  the  same  angle  as  the  glass  used 
(which  for  crown  glass  is  56  45),  we  obtain  an  additional  quan- 
tity by  laying  upon  it  a single  plate*  of  such  glass,  and  a further 
quantity  by  the  addition  of  a second,  third,  or  any  further  num- 
ber. The  quantity  of  light  added  by  each  succeeding  plate 
being,  however,  less  in  proportion  to  the  number  of  plates  through 
which  it  has  to  pass.  In  this  respect  the  single-image  Nichol’s 
prism  of  Iceland  Spar  is  decidedly  the  best  for  analysing,  as  by 
this  a great  variety  of  objects  may  be  exhibited/’  This  latter 
Nichol’s  prism  analyser  is,  therefore,  most  generally  used,  being 
mounted  in  a tube  by  which  it  may  be  revolved  in  front  of  the 
objectives,  the  subjects  for  examination  being  placed  in  the  rays 
of  polarized  light,  between  the  mirror  or  polarizer  and  the  objec- 
tive. From  the  optical  instrument  makers  may  be  obtained  trans- 
parent butterflies,  flowers,  and  other  objects  made  from  thin  films 
of  crystals,  of  selenite,  or  mica,  and  when  these  are  placed  in  the 
polariscope,  the  most  brilliant  variations  of  colour  are  projected 
on  the  screen  as  the  analyser  is  made  to  revolve. # 

THE  SPECTRUM, 

or  Dispersion  of  Light,  and  also  Spectrum  Analysis,  may  be  fairly 
couducted  by  the  oxy-hydrogen  lantern,  but  for  the  latter  purpose 
a special  kind  of  jet  is  required.  To  show  the  Spectrum  by  means 
of  the  lantern,  perhaps  no  way  is  more  effective  than  that  of  the 

* See  “ Light,"  a Course  of  Experimental  Optics,  by  Lewis  Wright. 


133 


THE  MAGIC  LANTERN  MANUAL. 


rainbow  as  an  effect  upon  a landscape  picture,  or  upon  such  a view 
as  Niagara  Falls.  To  accomplish  this  a second  lantern  is  indis- 
pensable, one  for  the  view,  the  other  for  the  rainbow.  The  view 


Fig.  91. 

is  shown  on  the  screen  by  the  one  lantern  in  the  usual  manner.  A 
piece  of  sheet  brass  or  tin,  in  which  is  cut  a semicircular  slit,  as 
shown  at  Fig.  91,  is  next  placed  in  the  second  lantern,  thereby 


Fig.  92. 

projecting  a semicircle  of  white  light.  A prism  must  now  be  placed 
in  front  of  the  objective,  which  will  cause  the  semicircle  of  white 
light  to  leave  the  screen,  and  probably  on  the  floor  or  the  ceiling 
it  would  be  seen,  but  not  as  before,  for  by  the  introduction  of  the 


SCIENTIFIC  PROJECTIONS . 


139 


prism  the  light  would  be  decomposed,  and  present  a fair  illustration 
of  the  colours  of  the  rainbow.  The  lantern  must  now  be  raised  in 
front  so  as  to  bring  the  effect  on  the  screen  into  its  proper  position, 
as  at  Fig.  92.  It  is  often  more  convenient  to  turn  the  lantern  side- 
ways  than  to  elevate  it  in  front,  and  by  using  the  prism  in  a vertical 
position  an  equally  good  effect  can  be  obtained,  but  a larger  prism 
is  rendered  necessary. 

THE  KALEIDOSCOPE. 

This  instrument,  the  invention  of  Sir  David  Brewster,  has  been 
for  years  before  the  public,  and  is  almost  an  universal  favourite.  Its 


Fig-  93- 


adaptation  to  the  lantern  has  been  accomplished,  notwithstanding 
very  many  difficulties.  Mr.  Darker,  of  Lambeth,  has  devoted  much 
time  and  attention  to  this  adaptation,  and  that  exhibited  at  the 
Royal  Polytechnic  was  of  his  manufacture.  It  may  be  briefly  de- 

10 


140 


THE  MAGIC  LANTERN  MANUAL. 


scribed  thus  : A pair  of  plain  mirrors,  fixed  inside  a brass  tube,  at 
each  extremity  of  which  is  placed  a lens,  the  one  placed  nearest  the 
lantern  condenser  being  a meniscus,  and  at  the  other  end  being 
piano  convex.  In  other  words,  it  forms  a lantern  objective,  with 
two  plain  mirrors  inserted  in  the  position  of  a V between  the  lenses. 
The  light  must  be  raised  above  the  centre  of  the  condensers,  and 
upon  the  proper  adjustment  of  the  light  and  the  exact  centring 
of  the  optical  arrangements  its  success  much  depends.  This  in- 
strument cannot  be  used  in  connection  with  the  lantern  with  any 
satisfactory  result,  except  by  lime  light,  and  even  then  to  no  large 
size.  One  great  difficulty  is  experienced  by  the  collection  of  mois- 
ture upon  the  plain  mirrors,  which  greatly  detracts  from  a perfect 
illumination.  In  the  Kaleidoscope  sometimes  a third  reflecting 
mirror  is  employed,  a cross  section  of  the  three  forming  an  equi- 
lateral triangle.  A pattern  or  design  produced  by  such  an  arrange- 
ment is  shown  at  Fig.  93.  Various  substances  may  be  introduced 
to  produce  different  effects,  such  as  broken  coloured  glass,  pins, 
needles,  etc.,  which  can  be  inserted  by  removing  the  meniscus  lens 
from  the  tube. 

TOTAL  REFLECTION. 

The  “ Illuminated  Cascade  ” will  well  repay  the  trouble  of  its 
production.  This  effect  was  shown  some  years  ago  at  the  Royal 
Polytechnic  Institution,  where  Mons.  Duboscq,  of  Paris,  erected  a 
very  elaborate  arrangement,  the  exhibition  causing  universal  admi- 
ration. To  exhibit  this  effect  on  a small  scale,  the  apparatus  neces- 
sary consists  of  a tall  glass  vessel,  supported  on  a stand,  and  placed 
in  front  of  the  condenser,  the  objectives  being  removed.  An  illus- 
tration is  given  at  Fig.  94.  The  vessel  a must  be  wholly  covered 
with  black  paper,  except  at  c,  where  the  rays  of  light  from  the 
condenser  enter,  and  are  brought  to  a focus  at  b,  which  is  a circular 
orifice,  from  which  a stream  of  water  issues  in  the  form  shown;  the 


SCIENTIFIC  PROJECTIONS. 


141 

rays  of  light,  being  carried  with  it,  are  reflected  from  side  to  side  of 
the  arched  column  of  water,  which  is  illuminated  in  a most  lovely 
manner  through  its  course.  If  various  coloured  glasses  be  inserted 


at  d,  the  effect  produced  is  still  more  beautiful.  To  insure  success, 
the  orifice  b should  be  perfectly  round  and  smooth,  allowing  the 
stream  to  issue  unbroken ; and  when  adding  more  water,  it  must 
be  done  very  quietly,  so  as  not  to  cause  a current,  or  the  effect 
will  be  lost. 

An  experiment  illustrating  the 

REFRACTION  OF  GLASS 

may  be  shown  as  follows : — After  preparing  a glass  plate  with 
burning  camphor,  as  previously  described,  draw  upon  it  a line  or 
an  arrow  about  2 inches  in  length.  This,  upon  being  inserted  in 
the  lantern,  will  show  a white  line  or  arrow  upon  the  dark  ground. 
Now  take  a strip  of  glass  about  f inch  broad  and  i thick,  insert 
it  in  front  of  the  slide  at  right  angles  to  the  arrow  or  line : so  long 
as  it  is  kept  at  right  angles,  no  refraction  will  be  seen ; but  on  in- 
clining it  so  that  the  rays  of  light  shall  pass  through  it  obliquely, 


io- — 2 


I42 


THE  MAGIC  LANTERN  MANUAL . 


a piece  of  the  arrow  or  line  will  appear  to  be  cut  out  and  moved 
to  one  side : the  thicker  the  glass  the  greater  the  displacement. 

THE  PERSISTENCE  OF  VISION 

may  be  illustrated  by  a little  instrument  styled  a Kaleidotrope.  It 
consists  of  a disc  of  tin  perforated,  as  shown  in  Fig.  95,  attached 
to  the  wood  block  by  means  of  a lateral  spiral  spring,  being  free  to 
revolve  upon  its  centre  point.  When  projected  on  the  screen 
nothing  more  is  seen  than  a number  of  white  spots,  but  upon  giving 


Eg-  95- 


motion  to  the  disc  by  a touch  of  the  finger,  circles  of  light  are  seen 
beautifully  interlacing  one  another.  The  principle  is  that  of  “ Per- 
sistence of  Vision,”  and  may  be  compared  to  the  boyish  experiment 
of  whirling  round  a lighted  stick,  and  so  causing  an  apparent  circle 
of  light. 

COLOUR  EXPERIMENTS 

form  a most  interesting  branch  of  science,  and  are  easily  con- 
ducted by  means  of  the  Magic  Lantern.  A series  of  such  experi- 
ments were  published  some  time  ago  by  Mr.  W.  B.  Woodbury,  from 
which  the  following  are  extracted.  Two  discs  of  thin  cardboard 
are  obtained,  in  each  of  which  must  be  cut  three  circular  apertures. 
Three  pieces  of  different  coloured  gelatine  are  now  attached  to  the 


SCIENTIFIC  PROJECTIONS. 


143 


backs  of  each  disc,  a yellow  piece  covering  one  aperture,  a red 
the  second  aperture,  and  a blue  piece  the  third;  so  that  upon 
looking  through  the  disc  it  will 
present  three  circles,  one  red,  one 
blue,  and  one  yellow.  Should  these 
discs  be  placed  in  a chromatrope- 
holder,  and  made  to  revolve  in 
opposite  directions,  the  secondary 
colours  will,  of  course,  be  seen 
(Fig.  96).  “ But  great  care  must 

be  taken,  in  choosing  the  blue,  to 

see  that  it  is  not  of  a purple  tint,  otherwise  no  approach  to  a 
green  will  be  obtained.  On  attaching  two  discs  to  one  circle  and 


Fig.  96. 


one  to  the  other,  the  red  being  over  the  blue  in  the  first,  we  then 
get  all  the  tertiary  colours.” 

An  instrument,  called  the  Chromodrome,  illustrated  at  Fig.  97, 


144 


THE  MAGIC  LANTERN  MANUAL, 


is  arranged  for  communicating  rapid  motion  to  discs  of  glass,  which 
have  various  designs  attached  in  coloured  gelatine.  At  Fig.  98 
we  have  a design  which  will  give  all  the  delicate  gradations  of  any 
colour  mixed  with  white  tints  in  steps,  whilst  Fig.  99  will  give  a 
continual  graduated  tint.  A series  of  thirty  different  designs,  and 
a short  Manual,  by  Mr.  John  Gorham,  on  the  Rudiments  of 
Colour  by  Rotation,”  together  with  an  apparatus  for  rotating  the 
designs,  is  supplied  by  A.  N.  Myers  & Co.,  London.  All  these 
may  be  copied,  and  exhibited  to  a large  audience  by  means  of  the 
lantern,  with  great  effect. 

Another  striking  way  of  showing  complementary  colours  is  by 
_ means  of  a set  of  slides  manu- 

factured by  the  Sciopticon 
Company,  and  consist  of  sheets 
of  perforated  zinc,  mounted 
with  sheets  of  coloured  gelatine 
between  glass  plates,  together 
with  a duplicate  design  without 
the  coloured  gelatine.  Two  of  these  are  shown  at  Figs.  100  and  10 1. 


Tig.  98. 


Fig.  99. 


Fig . IOO. 


Fig . 1 01. 


CHEMICAL  EXPERIMENTS. 

Most  of  the  chemical  experiments  usually  shown  before  classes 
can  be  conducted  in  the  lantern  with  great  success,  but  for  this 


SCIENTIFIC  PROJECTIONS, 


145 


purpose  it  is  necessary  that  the  slide  stage  shall  be  open  at  the 
top.  A tank  will  be  necessary,  which  may  be  made  of  two  plates  of 
white  glass,  kept  apart  by  a strip  of  india-rubber  about  half  an  inch 
thick,  bent  round  their  sides  and  secured  by  four  screw  clamps. 
Such  a tank  will  hold  almost  any  kind  of  solution,  and  is  very  ac- 
cessible for  cleaning.  A neater  apparatus,  is  shown  at  Fig.  102. 
A few  pipettes  will  also  be  required.  These  may  be  made  of  pieces 
of  glass  tube,  one  end  of  which  should  be  drawn  to  a fine  point ; 


Fig.  102. 


or  a useful  pipette,  shown  at  Fig.  103,  may  be  obtained,  provided 
with  an  elastic  ball.  The  experiments  which  come  under  the  above 
head  are  so  numerous  that  only  a few  will  here  be  given. 


Fig . 103. 


Part  fill  the  tank  with  water,  and  add  a solution  of  litmus,  till 
the  whole  becomes  of  a bluish-purple  tint ; now  by  dropping  into 
it  from  the  pipette  very  dilute  acid,  a cloudlike  effect  is  produced, 
and  ultimately  the  whole  becomes  red.  Now,  if  dilute  ammonia 
be  added  in  like  manner,  a change  is  brought  about,  and  the 
original  colour  is  restored. 


THE  MAGIC  LANTERN  MANUAL . 


14  6 

Fill  the  tank  with  dilute  alcohol,  and  add  drop  by  drop  of  almost 
any  of  the  aniline  colours  (Judson's  dyes).  The  effect  resembles  a 
tree  shooting  out  in  a variety  of  ways  and  branches;  and  by  using 
different  colours  at  the  sides  and  centre  the  effect  is  wonderfully 
increased. 

The  Silver  Tret  is  produced  by  partly  filling  the  tank  with  a 
dilute  solution  of  nitrate  of  silver.  A piece  of  copper  is  now  bent 
into  the  form  of  an  arc,  and  allowed  to  dip  into  the  solution.  It 
should  now  be  nicely  focussed  on  the  screen,  and  in  a very  short 
time  pure  silver  will  be  deposited  on  the  copper  wire  in  arbo 
rescent  form,  varying  in  form  in  proportion  to  the  strength  of  the 
solution. 

Precipitation  may  be  shown  with  the  same  solution  as  used  in 
the  silver  tree  experiment,  by  dropping  from  the  pipette  into  the 
solution  dilute  hydrochloric  acid,  when  very  dense  clouds  of  chlo- 
ride of  silver  will  be  produced,  which  will  ultimately  subside  to  the 
bottom  of  the  tank.  By  adding  strong  ammonia,  the  precipitate 
will  be  re-dissolved,  and  the  solution  become  clear. 

Crystallization  of  many  substances  is  well  worthy  of  notice. 
Thus,  if  a saturated  solution  of  sulphate  of  soda  be  placed  in  the 
tank,  and  a crystal  of  the  same  added,  the  whole  will  shoot  out 
into  a mass  of  beautiful  crystals. 

PHOTOGRAPHY. 

The  development  of  the  photographic  image  is  always  a fasci- 
nating experiment,  and  may  be  performed  without  much  trouble 
in  the  following  manner : In  the  first  place,  the  room  mnst  be  in 
perfect  darkness,  with  the  exception  of  the  light  of  a candle  filtered 
through  a sheet  of  coloured  gelatine  or  ruby  glass.  A strip  of 
glass,  say  4^  by  2 inches,  or  half  a quarter-plate  cut  length- 


SCIENTIFIC  PROJECTIONS, 


H 7 


ways,  is  better  for  experiment  than  a larger  plate,  as,  the  edges 
being  in  view  when  the  picture  begins  to  develop,  the  effect  is 
better  observed.  A thin  solution  of  india-rubber  in  benzole  or 
chloroform  should  now  be  applied  to  the  edges  of  the  glass  plate ; 
this  will  dry  almost  instantaneously.  Now  coat  the  glass  with  a 
collodion  emulsion,  better  procured  ready  prepared.  As  soon  as 
set,  it  may  be  dried  over  a spirit  lamp,  and  is  then  ready  for 
printing.  One  end  of  the  glass  plate  must  now  be  marked,  or  if 
the  emulsion  be  kept  a little  from  one  end,  this  will  serve  to  dis- 
tinguish it  after  printing.  This  precaution  is  necessary  so  as  to 
prevent  the  possibility  of  developing  the  picture  upside  down.  It 
must  now  be  placed  in  contact  with  a sharp  negative,  face  to  face 
the  length  way,  crossing  the  negative  and  the  marked  end  of  the 
prepared  plate  at  the  bottom.  It  may  be  held  in  position  in  an 
ordinary  pressure  printing-frame,  and  exposed  to  the  light  of  the 
lantern,  or  ordinary  gaslight.  The  exposure  will  vary  with  the 
nature  of  the  light  and  the  density  of  the  negative.  (See  instruc- 
tions for  printing  photographic  transparencies,  page  92.) 

So  soon  as  printed  and  the  light  lowered,  except  the  non-actinic 
light  above  mentioned,  it  may  be  taken  from  the  printing-frame. 
Now  flow  over  its  surface  a solution  of  water  and  alcohol  in  equal 
proportions,  and  after  wash  the  plate  in  a cup  of  water.  For  the 
development , a tank  must  be  used,  with  a piece  of  ruby  glass  in- 
serted between  it  and  the  condenser,  and  upon  turning  up  the 
light  of  the  lantern,  a ruby  disc  will  be  projected  on  to  the  screen. 
If  the  plate  be  now  placed  in  the  tank  (the  marked  end  at  the  top 
or  outside),  no  image  will  be  visible.  A clear  solution  of  pyro- 
gallic  acid  and  water,  three  grains  to  one  ounce,  is  now  poured 
into  the  tank  until  it  is  three  parts  full,  and  still  no  change  will 
be  apparent ; but  upon  the  application  of  a few  drops  of  a solution 
of  ammonia  and  bromide  of  potassium — 


148 


THE  MAGIC  LANTERN  MANUAL. 


(Liquid  ammonia  . . .1  drachma 

I Water 1 ounce,  mixed  in  equal 

* y 

j Bromide  potassium  . . 20  grains,  proportions, 

(Water 1 ounce,  > 

the  image  will  gradually  appear  and  very  soon  acquire  sufficient 
intensity,  when  it  must  be  removed  and  washed  in  a cup  of  clean 
water.  Another  tank  is  next  placed  in  the  lantern  without  the 
ruby  glass,  and  nearly  filled  with  a solution  of  hyposulphite  of 
soda.  The  plate  is  now  inserted,  when  it  will  immediately  be- 
come clear  and  more  transparent.  It  should  be  now  removed 
and  washed,  and  dried  over  a spirit  lamp,  when  it  may  be  shown 
as  any  other  transparency. 


CAPILLARY  ATTRACTION 

is  shown  by  a tank  (Fig.  102)  placed  in  the  lantern,  and  half 
filled  with  water  coloured  with  a few  drops  of  writing  ink,  so 
that  it  will  be  more  clearly  seen.  Now,  by  inserting  small  glass 


Fig.  104.  Fig.  105. 

tubes  vertically,  the  solution  will  rise  inside  the  tubes  in  propor- 
tion to  their  diameter.  Should  a series  of  glass  tubes  of  different 
diameters,  and  arranged  in  a line  on  a piece  of  wood,  be  inserted 
(see  Fig.  104),  the  different  heights  will  be  clearly  shown  on  the 
screen,  proportionately  with  the  .fineness  of  the  tubes.  A striking 


SCIENTIFIC  PROJECTIONS. 


149 


illustration  may  be  shown  by  means  of  two  glass  plates  attached 
to  a bar  of  wood,  so  that  two  of  the  edges  touch  each  other,  and 
the  other  two  are  some  i inch  apart  (Fig.  105).  When  these 
plates  are  inserted  in  the  tank,  the  coloured  water  will  rise  between 
the  plates  where  they  are  in  contact,  and  slope  away  with  a beau- 
tiful curve  as  the  plates  become  more  distant. 

EBULLITION. 

To  illustrate  that  liquids  in  the  spheroidal  state  and  the  metal 
plate  are  not  in  contact,  accurately  level  a smooth  flat  strip  of 
metal  about  midway  across  the  condensers  so  that  it  can  be  removed 
and  replaced  easily.  It  must  now  be  heated  by  a spirit  lamp  or 
other  convenient  method,  and  replaced,  when  a few  drops  of  water 
may  be  dropped  from  a pipette  upon  the  hot  plate;  the  water  will 
now  assume  the  spheroidal  state,  and  by  means  of  a fine  platinum 
wire  passed  into  the  globule,  the  liquid  may  be  kept  in  position, 
and  upon  focussing  this  accurately  on  the  screen,  a space  will  be 
distinctly  seen  between  the  globule  and  the  hot  plate. 

ELECTRICITY 

is  another  branch  of  science  which  can  be  illustrated  by  means  of 
the  lantern,  and  with  small,  simple,  and  inexpensive  apparatus 
fitted  to  the  lanterns,  many  experiments  can  be  exhibited  to  large 
audiences,  which  would  be  almost  impracticable  to  illustrate  in 
any  other  way,  except  at  a great  cost.  The  apparatus  being  small, 
great  battery  power  is  seldom  required.  The  bichromate  battery 
offers  the  best  facility  to  the  lecturer : this  may  be  separate,  of 
usual  form,  or  it  may  be  for  convenience  and  portability  fitted  to 
the  Sciopticon,  as  is  the  one  in  use  by  the  writer,  which  was 
devised  and  constructed  by  Mr.  W.  Watts.  It  is  fitted  into  the 
hollow  space  in  the  lower  portion  of  the  front  of  the  Sciopticon, 


THE  MAGIC  LANTERN  MAN  HAL. 


150 

and  consists  of  two  cells  5 inches  long  by  2 \ inches  wide.  The 
outside  casing  is  made  of  zinc  plates,  forming  a box,  each  pole  of 
the  battery  terminating  in  a slight  projecting  spring,  so  that  when 
the  battery  is  put  into  its  place  these  springs  press  against  two 
brass  studs,  which  project  a little  inside  the  Sciopticon  base,  and 
being  screwed  through  the  base  from  the  outside,  have  each  sol- 
dered on  to  them,  in  a vertical  position,  a split  tube  similar  to  a 
penholder  socket.  The  terminals,  which  are  screwed  to  the 
exhibiting  tank-frame,  being  each  provided  with  a brass  leg,  the 
tank  has  only  to  be  pushed  down  into  its  place,  each  leg  sliding 
into  its  respective  socket,  and  the  connections  are  complete. 
Should  it  be  desirable  to  reverse  the  poles,  as  in  some  instances 
is  necessary,  this  can  be  done  in  a moment  by  simply  withdraw- 
ing the  exhibiting  tank  from  its  sockets  and  reversing  its  position. 
As  this  battery  holds  only  a small  quantity  of  solution,  it  will  not 
keep  up  an  energetic  action  so  long  as  the  conventional  bulbous 
form  of  battery,  but  it  possesses  for  lantern  requirements  sufficient 
lasting  power,  also  the  feature  of  compactness  and  portability  dis- 
pensing with  wires,  which  are  liable  to  be  pulled  out  or  become 
entangled  in  the  dark. 

The  solution  cannot  be  spilt,  as  the  battery  is  provided  with 
suitable  lid  and  india-rubber  pad,  also  two  thumb-screws  which 
effectually  tighten  all  down  and  prevent  any  leakage. 

The  lantern  being  no  more  bulky  with  this  attachment  than 
without  it,  and  consequently  requiring  no  extra  packing,  together 
with  its  extreme  facility  for  manipulation,  make  it  very  desirable 
and  useful  attachment. 

ELECTRO  DEPOSITION. 

The  deposition  of  one  metal  upon  another  by  electricity  or 
magnetism — almost  invariably  the  more  precious  metals  being 


SCIENTIFIC  PROJECTIONS. 


15 


deposited  upon  the  baser — has  of  late  years  become  so  extended 
as  to  assume  the  proportions  of  a large  and  lucrative  trade,  di- 
vided into  several  branches : enormous  quantities  of  nickel  and 
copper,  thousands  of  ounces  of  silver  and  gold,  besides  numerous 
other  metals,  are  being  consumed  annually  in  the  various  processes 
of  electro  deposition.  Scarcely  a trade  exists  in  which  this  useful 
art  is  not  connected  in  some  way  or  other,  from  the  massive 
copper-covered  roller  of  the  calico  printer,  to  the  most  elaborate 
and  costly  works  of  art ; and  faithful  copies  of  the  most  antique 
works  of  the  ancients  are  being  constantly  reproduced  by  those 
firms  who  have  made  this  branch  of  the  art  their  speciality.  It 
cannot,  therefore,  but  be  interesting  to  some  of  our  readers  to  see 
and  learn  something  of  this  important  branch  of  industry,  which 
came  into  existence  about  the  same  period  as  its  sister-art,  photo- 
graphy : the  one  owing  its  principle  of  action  to  light,  the  other 
to  electricity  or  magnetism  ; both  illustrating  some  of  the  most 
wonderful  of  nature’s  phenomena. 

It  is  in  this  as  in  other  portions  of  this  work  neither  our  forte 
nor  intention  to  attempt  an  exhaustive  treatise  upon  this  subject, 
our  desire  being  simply  to  direct  the  attention  of  the  student  by 
as  brief  a description  as  a clear  explanation  will  admit,  to  a few 
interesting  experiments,  projected  on  the  screen,  illustrative  of 
electro  deposition. 

For  this  purpose  a tank  and  battery  will  be  required  : the  tank 
should  have  two  brass  terminals,  one  screwed  into  each  side  at  the 
top  of  the  wood  frame,  to  receive  the  wires  from  the  battery,  the 
most  convenient  form  of  which  is  the  bichromate ; this  should  be 
at  least  a pint  in  capacity.  Next  procure  about  four  grains  of  fine 
gold,  rolled  very  thin,  about  the  size  of  a postage-stamp,  also  a piece 
of  copper  gauze  about  the  same  size ; this  should  be  flattened  a little 
with  a hammer,  to  close  up  the  texture.  Both  the  gauze  and  gold 


152 


THE  MAGIC  LANTERN  MANUAL. 


plate  must  have  now  a piece  of  thin  copper  wire,  about  4 inches 
long,  soldered  to  their  respective  edges ; then  twist  up  the  free  ends 
into  a loop,  and  screw  up  tight  between  the  terminals  and  wood 
frame.  The  wires  may  now  be  bent,  so  as  to  let  the  gold  plate 
or  anode,  and  copper  gauze  or  cathode,  occupy  the  centre  of  the 
tank  without  touching  each  other.  Now  nearly  fill  the  tank  with 
water,  and  drop  into  it  a piece  of  cyanide  of  potassium,  about  the 
size  of  a horse-bean ; whilst  it  is  dissolving,  connect  up  the  bat- 
tery by  attaching  the  wire  from  the  carbon  plate  to  the  gold  ter- 
minal, and  the  wire  from  the  zinc  plate  to  the  copper  terminal ; 
lower  the  zinc  plate  into  the  battery  solution,  and  electrolysis  will 
commence  immediately.  If  the  anode  and  cathode  or  electrodes, 
as  we  will  now  call  them,  have  been  adjusted  parallel  to  each 
other,  they  can  be  accurately  focussed  upon  the  screen  : the  image 
will  now  appear  as  a large  black  square  and  a trelliswork  side  by 
side ; and  if  the  battery  power  be  brisk,  globules  of  hydrogen  will 
be  evolved  from  the  anode  with  great  rapidity,  very  shortly  the 
edges  of  which  will  become  frayed ; and  as  the  action  goes  on  a 
number  of  perforations  will  gradually  extend  from  the  edges  to  the 
centre  of  the  plate ; and  as  it  becomes  more  diaphanous  through 
the  continued  action,  the  peculiar  texture  or  crystalline  perfora- 
tions will  be  more  easily  observed;  and,  as  the  action  is  still 
further  continued,  these  perforations  will  gradually  enlarge  until 
small  particles  of  the  anode  will  become  detached  and  fall  to  the 
bottom  of  the  tank.  While  this  is  going  on  with  the  anode,  the 
spaces  in  the  cathode  are  as  gradually  becoming  filled  up;  and  if 
the  action  be  allowed  to  proceed  indefinitely,  the  cathode,  or  a 
portion  of  it,  will  become  so  filled  up  as  to  almost  entirely  prevent 
the  transmission  of  light,  whilst  the  anode  will  disappear  alto- 
gether. The  liquid  in  the  tank  will  now  have  become  formed  into 
a double  cyanide  of  gold,  but  it  will  only  have  a small  quantity 


SCIENTIFIC  PROJECTIONS. 


153 


of  gold  suspended  in  the  solution ; because,  almost  as  fast  as  it 
can  be  dissolved  from  the  anode,  it  will  become  deposited  upon 
the  cathode.  This  deposit  will  be  of  a brownish-yellow  colour,  it 
being  necessary  to  raise  the  temperature  of  the  solution  to  about 
140  degrees  to  produce  the  proper  gold  colour  of  deposit.  This 
could  readily  be  done  by  the  aid  of  a spirit  lamp,  and  by  observing 
a few  other  chemical  conditions ; but,  as  this  would  not  improve 
the  effect  of  the  chemical  action  upon  the  screen,  we  may  as  well 
dispense  with  the  extra  trouble,  our  object  being  to  utilize  for 
our  purpose  only  those  effects  which  the  transmission  of  light  will 
demonstrate. 

Magnetic  and  diamagnetic  phenomena  may  be  demonstrated 
by  use  of  a small  electro  magnet,  shown  attached  to  a light  wood 
frame  at  Fig.  106.  The  magnet  should  be  of  soft  common  iron, 
with  a hole,  as  shown  in  the  illustration,  through  which  articles  to 


be  operated  upon  may  be  passed.  The  frame  is  to  be  placed  in 
the  lantern  and  the  poles  of  the  magnet  focussed  upon  the  screen, 
and  with  a small  battery  power  some  very  interesting  effects  may 
be  illustrated.  Fine  iron  filings,  if  dropped  gently  through  the  hole 
at  the  top  between  the  poles,  will  attach  themselves  to  each  pole 
and  give  a very  curious  outline  on  the  screen,  increasing  in  size  as 
the  filings  are  dropped  through,  until  at  length  they  meet  together 


154 


THE  MAGIC  LANTERN  MANUAL. 


and  form  the  magnetic  curve.  By  fitting  into  the  hole  of  the 
frame  a cork,  through  which  a brass  wire  is  made  to  pass,  needles 
and  other  small  articles  may  be  suspended  by  a silk  thread.  In 
the  illustration  a small  disc  is  shown  suspended  in  the  manner 
described.  When  a needle  or  iron  disc  is  suspended  between  the 
poles  of  the  magnet,  being  attracted  by  them,  it  takes  up  a position 
of  rest,  joining  the  poles  as  illustrated;  but  a rod  or  disc  of  bis- 
muth, on  the  other  hand,  would  be  repelled  by  the  poles  of  the 
magnet,  and  would  take  up  its  position  of  rest  at  right  angles  to 
the  poles,  thus  placing  themselves  equatorially  and  illustrating 
diamagnetism.  Pieces  of  iron,  copper,  alum,  sulphur,  paper,  char- 
coal, and  small  tubes  filled  with  various  solutions,  such  as  those 
of  iron,  cobalt,  water,  alcohol,  etc.,  etc.,  are  all  suitable  for 
suspending  and  operating  upon. 

The  electro  decomposition  of  water  is  effected  by  sending  a 
current  of  electricity  from  three  or  four  cells  through  water  slightly 
acidulated  by  sulphuric  acid.  Through  the  bottom  of  the  tank 
two  platinum  wires  should  be  fixed,  projecting  some  distance  into 
the  solution ; two  test-tubes  filled  with  the  acidulated  water  should 
now  be  introduced  into  the  tank,  one  standing  over  each  platinum 
terminal,  which  will  thus  project  into  the  tubes  say  f inch : 
as  soon  as  the  current  of  electricity  is  caused  to  pass,  from  these 
wires,  bubbles  will  be  seen  to  rise,  and  soon  one  test-tube  will  be 
filled  with  hydrogen  gas,  the  other,  in  which  oxygen  will  be  present, 
will  only  be  half  full  in  the  same  time. 

THE  END. 


DALZIEL  BROTHERS,  CAMDEN  PRESS,  LONDON,  N W, 


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AMERICAN  PHOTOGRAPHIC  ALMANAC  FOR  1868  25 

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AMERICAN  ALMANAC  OF  PHOTOGRAPHY  FOR  1864  Edited  by  Charles 

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